Immunoglobulin cleavage fragments as disease indicators and compositions for detecting and binding such

ABSTRACT

The invention relates to antibody compositions and use of the composition to detect disease processes associated with elaboration of proteases. The reagents are directed to assessing an IgG breakdown product that is the result of such proteolytic cleavage. The invention further relates to the use of a therapeutic immunospecific for IgG protease cleavage products to restore effector function to antibody compositions that are subject to protease cleavage.

CLAIM TO RIGHT OF PRIORITY

This application claims priority to U.S. patent application Ser. No.12/185,333 filed 4 Aug. 2008, and U.S. Provisional Application No.60/955,162, filed 10 Aug. 2007, the contents of which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to diagnostic and prognostic indicators andmethods and reagents for their detection. The invention further relatesto methods of monitoring the natural history of disease in a patient aswell as methods for treating pathological conditions by vaccinating oradministering antibodies specific for immunoglobulin cleavage sites torestore effector function of antibodies.

2. Description of the Related Art

In medicine, a biomarker is a biochemical substance that can be used tomeasure the progress of disease or the effects of treatment, that is, adiagnostic or prognostic indicator. One example is hemoglobin A1c whichserves as a recent record of the excursion of blood glucose away fromideal levels as well as the duration of such excursions for glycemiccontrol in diabetic patients.

Circulating immunoglobulins, and specifically those antibodies of theIgG class, are major serum proteins. It is well-known that humanproteases are associated with inflammatory, proliferative, metastatic,and infectious diseases. Human proteases such as matrixmetalloproteinases (MMPs) and neutrophil elastase cleave the IgGs heavychain polypeptide at a residue unique to each protease as do bacterialproteases such as glutamyl endopeptidase (Staph. aureus) orimmunoglobulin degrading enzyme of streptococcus (Strep. pyogenes). Thecleavage sites in the heavy chain are clustered around the region termedthe hinge domain, where the interchain disulfide linkage of the twoheavy chains occurs. The region below the hinge constitutes the Fcregion and comprises binding sites responsible for the effectorfunctions of IgG. In the case of microorganisms, protease expression isa potential adjunctive virulence pathway allowing organisms to avoidopsonization (Rooijakkers et al. Microbes and Infection 7: 476-484,2005) in so far as the proteolytic release of the Fc domain by cleavagebelow the hinge effectively neutralizes functions that would otherwiselead to the targeting and killing of that pathological cell. Thus, theelaboration of specific proteases may be representative of a myriad ofdiseases states including cancer, inflammation and infectious diseases.

That IgG degradation is enhanced in pathologic in vivo environments asevidenced by the presence of natural IgG autoantibodies that bind to thecleaved hinge domain (Knight et al., 1995; Nasu et al., 1980; Persselinand Stevens, 1985, Terness, et al. 1995 J Immunol. 154: 6446-6452).These autoantibodies also bind the Fab and F(ab′)₂ fragments generatedby several proteinases (including papain and pepsin), with particularlystrong reactivity to the lower hinge domain remaining as C-terminalresidues in F(ab′)2 molecules (Terness et al., 1995). The detection ofthe actual cleavage products have been reported (Fick et al., 1985;Goldberg and Whitehouse, 1970; Waller, 1974) but a robust assay whichwould allow these fragments to serve as biomarkers has not beendeveloped possibly due to the low concentrations in serum resulting fromrapid clearance of the various fragments or to technical problems indetecting the fragments amidst the large amount of intact immunoglobulinin blood and tissues. A specific antibody was prepared (Eckle, et al.1988. Adv. Exp. Med. Biol. 240: 531-534) for detection of humanneutrophil elastase cleaved Fc domaindetected Fc at a medianconcentration of 0.62 ug/ml directly in synovial fluid of rheumatoidarthritis patients but not in synovial fluid from patients with othertypes of joint disease.

Therefore, the ability to assess the type and amount of IgG cleavageproduct(s) in the bodily fluids or blood of subjects could be used as abiomarker of specific disease activity. Specific reagents and methodsfor such determinations would provide useful tools for diagnostic andprognostic medical assays. Further, the ability to correct loss of IgGfunctions in vivo due to cleavage and the ability to compensate theprocess of IgG cleavage in the body of subjects suffering from proteasespecific disease activity has not been heretofore envisioned as atherapeutic strategy.

SUMMARY OF THE INVENTION

The invention relates to reagents and use of the reagents to detect adisease process associated with elaboration of proteases, whichproteases are manifestations of the disease pathology as well as agentswhich limit host immunological defenses. In one aspect of the invention,the reagents and use of the reagents in an assay, detect antibodieswhich are specific for targets related to the disease pathology. Thereagents are directed to assessing an IgG breakdown product that is theresult of such proteolytic cleavage.

In another embodiment of the invention, the methods of the invention aredirected to detection of an IgG cleavage product which is characterizedby 1) having a molecular weight which is comparable to an intactmammalian IgG under physiological conditions and 2) being separable intotwo fragments which comprise an antigen binding fragment and a 32 kDafragment under denaturing but non-reducing conditions and 3) does notexhibit ADCC activity in an in vitro assay. In one aspect of the methodof detecting the IgG cleavage product of the invention, a specificreagent capable of detecting the cleavage product is provided, whichreagent is at least one antibody capable of binding to said cleavageproduct.

In another embodiment of the invention, disease specific cleavage sitepeptides representing the newly created C-terminal sequence of an IgGcleavage product are provided. These peptides are also useful forimmunizing, panning, and selection of the anti-IgG cleavage productantibody of the invention. In one aspect, the peptide is selected fromthe group consisting of at least five (5) contiguous amino acidsselected from the human IgG hinge region sequences of SEQ ID NO: 1, 2,3, or 4 that are on the amino terminal side of a protease cleavage site.In one embodiment, the polypeptides are selected from those of SEQ IDNOs. 5-11 and N-terminal truncations thereof. In another aspect, amethod of designing a peptide immunogen based on the proteolyticcleavage site of a human IgG molecule is provided.

In one embodiment of the invention, methods of preparation of ananti-IgG cleavage product antibody of the invention are providedincluding nucleic acid sequences, vectors, and host cells for therecombinant production of anti-IgG cleavage product antibodies. Inanother aspect of the method of manufacturing the anti-IgG cleavageproduct antibodies, immunized host animals are provided which animalsprovide an antibody of the invention. In a particular embodiment, theanimal is a human and the anti-IgG cleavage product is generated byadministration of a cleavage site peptide immunogen selected from thegroup consisting of at least five (5) contiguous amino acids selectedfrom the human IgG hinge region sequences of SEQ ID NO: 1, 2, 3, or 4that are on the amino terminal side of a protease cleavage site such asthe sequences of SEQ ID NOs. 5-11 and N terminal truncations thereof.

In another embodiment of the invention, a kit for detection of anti-IgGcleavage product is provided comprising anti-IgG cleavage productantibodies of the invention for use in diagnosis or monitoring a diseasecharacterized by the production of IgG cleaving proteases.

A further embodiment of the invention, is a method of administering ananti-IgG cleavage specific antibody to a patient as a method oftreatment, thereby restoring effector functions to a therapeuticantibody composition which has been subjected to protease degradation.In accordance with the method, effector function is restored to the IgGcleavage product by administering the antibodies of the presentinvention which specifically bind to the IgG cleavage product.

In another aspect of the invention, a human suffering from a diseasecharacterized by the elaboration of disease specific proteases, can betreated by administration of a cleavage site specific peptide immunogenselected from the group consisting of at least five (5) contiguous aminoacids of the human IgG hinge region sequences of selected from SEQ IDNO: 1, 2, 3, or 4; and that are positions on the amino (N) terminal sideof a protease cleavage site such as the sequences of SEQ ID NOs. 5-11and N-terminal truncations, species homologs and chemical homologsthereof, to restore effector functions of IgG cleavage products in suchpatient. In a specific embodiment, the cleavage site specific peptideimmunogen is represented by a peptide fragment that is N-terminal to thecleaved human IgG1 terminating with amino acid Glu233 (EU numbering),and the disease is selected from a S. aureaus infection characterized bythe release of glutamyl endopeptidase I (GluV8), or neutrophilic releaseof cathepsin G. In another embodiment, the cleavage site specificpeptide immunogen is represented by a peptide fragment which isN-terminal cleaved human IgG1 terminating with amino acid Pro232 (EUnumbering), and the disease is a form of human cancer characterized bythe release of MMP-3 or MMP-12. In another embodiment, the cleavage sitespecific peptide immunogen is represented by a peptide fragmentN-terminal to the IdeS of Streptococcus pyogenes cleaved human IgG1terminating at Gly236 (EU numbering), and the disease is a Streptococcusspp infection.

In another embodiment of the invention, a kit is provided comprisinganti-IgG cleavage product antibodies of the invention and instructionsfor use.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 depicts the various domains of a typical mammalian IgG classantibody showing their relationship to the hinge and the pepsin andpapain cleavage products defined as Fab, F(ab′)₂, and Fc.

FIG. 2 shows four individual Agilent Biosizing microcapillaryelectrophoresis analyses as gel images at times during each of theproteinase digests of a human IgG1κ antibody, Mab1, by 1% w/w of humanMMP-3 (A), streptococcal IdeS (B), staphylococcal glutamyl endopeptidaseI (C) and human neutrophil elastase (D) at 37° C. Standards on each gel(lane 1) correspond to an intact human/murine chimeric IgG1 and knowncleavage fragments.

FIG. 3 shows the sequence of the human IgG1 heavy chain around the hingeregion; the positions of major proteolytic cleavages are indicated byarrows.

FIG. 4 is a western blot showing the time course of biotinylatedmurine/human IgG degradation by wound exudate.

FIG. 5 a graph showing the relative specificity of the antiseragenerated in rabbits immunized with fragments of human IgG enzymaticallygenerated from three different proteases: MMP-3, V8, and IdeS. Rabbitswere immunized with conjugated peptides having the sequences TCPPCPAP,residues 7-14 of SEQ ID NO: 1 corresponding to the MMP-3 cleavage site;TCPPCPAPE, residues 7-15 of SEQ ID NO: 1 corresponding to the glutamylendopeptidase site; and TCPPCPAPELLG, residues 7-18 of SEQ ID NO: 1corresponding to the IdeS site. ELISA reactivity of three individualrabbit polyclonal anti-cleavage site specific peptide antibodypreparations were tested for their ability to bind with F(ab′)₂fragments of Mab3 IgG1κ, as well as ScIgG and intact IgG. The F(ab′)₂fragments were generated with human recombinant MMP-3, staphylococcalglutamyl endopeptidase I and recombinant IdeS from Strep. pyogenes. Theantibody preparation showed binding to scIgG and F(ab¹)₂ but not tointact IgG. Bars correspond to the mean±standard deviation of threereplicate wells.

FIG. 6 is a Western blot showing the reactivity of rabbit polyclonalantibody preparations with antibody digests: Mab3 human IgG1 intact orthat had been partially digested with MMP-3, glutamyl endopeptidase (V8)or IdeS was separated by SDS-PAGE followed by immunoblotting, where (A)was blotted with anti-human IgG (H+L) [lanes 1-4] or anti . . . LLGrabbit polyclonal [lanes 6-10]. (B) was blotted with anti . . . PAP[lanes 2-5] or anti . . . APE [lanes 7-10]. The blots were cut prior toincubation with antibodies through lane 5 in panel A and lane 6 in panelB to allow for detection with the individual antisera.

FIG. 7 is a western blot developed using the RAH-1 reagent on samplesfrom an analysis of IgG degradation in the synovial fluid from 5 RApatients and compared to samples from in vitro proteolytic digests of amonoclonal IgG1 with MMP-3, glutamyl endopeptidase (V8) and IdeS.

FIG. 8 shows the serum concentration over time of various proteolyticcleavage fragments, intact IgG, scIgG and F(ab′)₂; after injection ofthe specified purified fragments into mice, measured using the goatanti-human IgG (H+L).

FIG. 9 is a dot plot of the individual values of scIgG detected by thereagent RAH-1 in human serum samples from patients diagnosed with thediseases as indicated as compared to that in a group of normal humanserum samples where the lines indicated mean values in each group.

FIG. 10 shows the concentration of scIgG in diluted serum of 10individuals with rheumatoid arthritis (RA) and an equal number ofhealthy, normal controls detected with reagent RAH-1 using an improvedversion of the ELISA; “(2)” in the RA group signifies that the samevalue was obtained in two separate individuals.

FIG. 11 shows the relative reactivity of rabbit monoclonal antibodytargeting cleavage fragments from human IgG1 hinge as peptide analogsand to antibody fragments terminating at the residue specified (see FIG.3).

FIG. 12 shows the concentration dependence of three different rabbitmonoclonal antibodies targeting cleavage fragments of human IgG1 hingein restoring complement-dependent cell lysis (CDC) to F(ab′)₂ created bydigesting IgG1 with IdeS compared to a rabbit polyclonal prepared tocleavage peptide analogs (rb poly).

FIG. 13 shows the mean log colony bacterial count and SEM in the whiffleball after inoculation with Staph. aureaus of control rabbits (blackline) vs. immunized rabbits (dashed line).

FIG. 14 is Kaplan Meier survival plot for rabbits inoculated with Staph.aureaus showing the control rabbits (black line) and immunized rabbits(dashed line).

FIG. 15 shows the change in tumor volume over time for five groups ofmice implanted with human breast carcinoma cells (MDA-MB231) and treatedwith either a tumor targeted Mab (860) alone (solid triangles); aprotease treated preparation of 860, 860 scIgG (closed circles); thecleavage site specific antibody preparation 2095-2; the 860 scIgG plusthe cleavage site specific antibody preparation 2095-2; or PBS (opencircles).

FIG. 16 shows the effect on circulating platelet numbers of ananti-platelet integrin Mab (c7E3) or proteolytic cleavage products ofthe Mab, administered alone and in combination with anti-cleavage sitemAb, 2095-2, on platelet counts in dogs, where each point represents themean±SD of the determinations of three animals.

BRIEF DESCRIPTION OF THE SEQUENCE LISTING

SEQ ID NO: DESCRIPTION 1 Human IgG1 hinge region 2Human IgG4 hinge region 3 Human IgG2 hinge region 4Human IgG3 hinge region 5 MMP-3 and MMP12 cleavage peptide 6Glutamyl endopeptidase 1 and Cathepsin G cleavage peptide 7IdeS cleavage peptide 8 Plasmin cleavage peptide 9 HNE cleavage peptide10 Pepsin and MMP-7 cleavage peptide 11 Papain cleavage peptide 12IdeS analogue cleavage site peptide immunogen, TAPPAPAPELLG 13IdeS analogue cleavage site peptide, TSPPSPAPELLG 14IdeS false analogue cleavage site peptide, TSPPSPAPALLG 15IdeS false analogue cleavage site peptide, TSPPSPAPEALG 16Glutamyl endopeptidase cleavage site analogue peptide, CTSPPSPSPAPE

DETAILED DESCRIPTION OF THE INVENTION Abbreviations

Abs=antibodies, ADCC=antibody-dependent cell-mediated cytotoxicity;CDC=complement directed cytoxicity; HNE=human neutrophil elastase;IdeS=immunoglobulin degrading enzyme of S. pyrogenes; Ig=immunoglobulin;Mab=monoclonal antibody; MMP=matrix metalloprotease ormetalloproteinase; N-terminal=amino terminal; scIgG=single cleaved IgG;SA=streptavidin; GluV8=glutamyl endopeptidase I from Staph. aureus.

DEFINITIONS

Antibody fragments; Fab, F(ab′)₂, and Fc are terms describingproteolytic cleavage products of IgG antibodies which may be furtherdissociated by reduction of the disulfide bonds between the heavy chains(the core hinge region). Classic proteolytically generated antibodyfragments, include: Fab (e.g., by papain digestion), Fab′ (e.g., bypepsin digestion and partial reduction) and F(ab′)₂ (e.g., by pepsindigestion), facb (e.g., by plasmin digestion), pFc′ (e.g., by pepsin orplasmin digestion), Fd (e.g., by pepsin digestion, partial reduction andreaggregation), where reduction removes the disulfide linkage betweencysteine residues forming interchain linkages (refer to FIG. 1). As theFc fragment was described as a papain cleavage fragment and becausepapain cleaves human IgG1 at residue 224 (EU numbering), which isN-terminal to the hinge, the Fc fragment is assumed to retain the hingeand the disulfide linkages between the heavy chains, however, due to thehigh degree of interchain association between the heavy chain CH2-CH3domains in the antibody, a dimeric structure is retained even in theabsence of the disulfide (hinge) bonds. Thus, as used herein “Fc” refersto the dimeric structure formed by association of the heavy chainCH2-CH3 segments whether covalently linked or not. It will be understoodthat the non-covalently associated Fc may be distinguished from thedisulfide linked Fc by its ability to undergo dissociation into CH2-CH3monomers in the presence of a denaturant such as a detergent.

Human antibodies are immunoglobulins which basic structure is a dimer oftwo heterodimers, where the heterodimers are each comprised of a heavyand a light chain polypeptide.

The terms “proteolytic”, “protease”, “proteinase” and “proteolyticenzyme” are used interchangeably and mean an agent, e.g. enzyme, whichis able to cleave a polypeptide chain producing two or more fragments,where the enzyme acts under normal temperature and under physiologicalconditions or physiologically compatible conditions. Physiologicalconditions include any temperature, buffer, cation, anion, substrate,catalyst, pH, cofactor, or the like which is naturally found in the bodyof a living mammal whether in health or disease. However, the proteasemay be derived from a non-mammalian source such as from a pathogen whichmay be of any type of life form. Proteases are hydrolases that act onpeptide bonds.

By “scIgG” or “single cleaved IgG” is meant any immunoglobulin class Gmolecules having a heterodimeric structure comprising two heavy chainsand two light chains, where one of the heavy chains has been subjectedto proteolytic cleavage on a single heavy chain while the second heavychain remains intact.

By “upstream” relative to an amino acid sequence written from theN-terminal to the C-terminal residue is meant the residues in thesequence towards the N-terminus from a given residue. Conversely, by“downstream” relative to an amino acid sequence is meant the residues inthe sequence towards the C-terminus from a given residue.

Antibody Functions by Substructure

In general, immunoglobulins, antibodies are proteins which consist ofregions of continuous polypeptide chains comprising approximately 100amino acids, and each about 10-11 kDa, which show a characteristicallyfolded globular domain and represent different elements of thestructure. For immunogammaglobulins (IgGs), these domains are groupedtogether into segments; the Fab segment is comprised of a light chainvariable joined to a light chain constant region in a single chainlinked through a disulfide bond to the heavy chain first constant region(CH1) which is contiguous with the heavy chain variable region; Fc iscomprised of two contiguous heavy chain constant regions (CH2 and CH3)linked through interchain disulfide bonds in the hinge region. Studieshave shown that proteases, such as papain and pepsin, preferentiallycleave antibodies at sites which are between the segments. Two identicalFab segments connected via the hinge region to one Fc segment, thus forma Y-shaped conformation of the 150 kDa structure (see FIG. 1). Fabsegments generated using papain typically have a molecular weight of 46kDa, nonreduced F(ab′)₂ typically have a molecular weight of 90-100 kDa,and nonglycosylated, nonreduced Fc will have an apparent molecularweight of approximately 50-60 kDa. However, as each antibody species,and each subclass of antibody within a species, is slightly different,the exact nature and location of the cleavage and cleavage products arevariant.

Antigen binds to antibodies via an antigen binding site in the variabledomains of each pair of light and heavy chains (FIG. 1). Othermolecules, known as effector molecules or cells, bind to other sites inthe remainder of the molecule, i.e. other than the antigen bindingsites, and this portion of antibody includes the more invariantimmunoglobulin sequences, “the constant portion” of an antibody, suchsites being located particularly in the Fc region constituted by theportions of the heavy chains extending beyond the ends of the lightchains: the upper hinge, lower hinge, CH2 and CH3 domains.

Antibodies have several effector functions mediated by binding ofeffector molecules. For example, binding of the C1 component ofcomplement to antibodies activates the complement system. Activation ofcomplement is important in the opsonisation and lysis of cell pathogens(a process called complement-mediated cytotoxicity or CDC). Theactivation of complement stimulates the inflammatory response and mayalso be involved in autoimmune hypersensitivity. Further, antibodiesbind to cells via the Fc region, with a Fc receptor site on the antibodyFc region binding to a Fc receptor (FcR) on a cell. There are a numberof Fc receptors which are specific for different classes of antibody,including IgG (gamma receptors), IgE (eta receptors), IgA (alphareceptors) and IgM (mu receptors). Binding of antibody to Fc receptorson cell surfaces triggers a number of important and diverse biologicalresponses including engulfment and destruction of antibody-coatedparticles, clearance of immune complexes, lysis of antibody-coatedtarget cells by killer cells (called antibody-dependent cell-mediatedcytotoxicity, complement-directed cytotoxicity, or ADCC), release ofinflammatory mediators, placental transfer and endothelial cell reuptake(via neotal Fc receptor or FcRn) and control of immunoglobulinproduction.

The sequences around the hinge domain are conserved among IgG isotypes(SEQ ID NO: 1-4) and among mammalian species generally. The IgG1 (SEQ IDNO: 1) and IgG3 (SEQ ID NO: 1) isotype comprise a Leu-Leu pair that is astructural motif for binding to Fcγ receptor(s) and for Fc effectorfunctions. Other residues downstream of the “hinge core” which typicallycomprises at least one cysteine separated by two non-cysteine residues,are also conserved.

Applicants have discovered that a cleavage product, scIgG, of human IgG1is formed by human and bacterial proteases when proteolysis occurs onone of the two heavy chain polypeptides that comprise an IgG, while notdisrupting the overall composition of the heterodimeric molecule.Secondly, applicants have determined through kinetic analysis ofproteolytic attack on human heavy chain constant region-containing IgGmolecules, that scIgG is likely the more abundant product of in vivoproteolysis found in the serum than are other fragments. The existenceof scIgG as a proteolytic intermediate leading to F(ab′)₂ duringproteolysis of IgG has been noted previously for the MMP-3 enzyme(Gearing A J H et al, Immunol. Lett. 81: 41-48, 2002). Cleavage of IgGby a streptococcal protease, IdeS, was also noted to produce a productresembling intact IgG by size-exclusion chromatography (Vincents B etal, Biochemistry 43: 15540-15549, 2004). However, no functionalcharacterizations of this intermediate were reported nor were methodsfor detecting the scIgG in biological samples provided.

Applicants have further demonstrated that, in vivo, scIgG, exhibits aserum half-life compatible with assessment of disease activity over aperiod of several days to months, thereby enabling the use of scIgG as amarker of latent or suppressed disease processes, or could be used tounderstand the recent natural history and response or recovery from adisease.

Briefly, applicants have discovered that the kinetics of proteolyticcleavage under physiological conditions lead to a larger proportion ofproteolytically cleaved IgG being in the scIgG conformation than specieswhich are products of multiple cleavage events, such as the F(ab′)₂ (seeFIG. 1). In the process of testing a large number of proteases, it wasdetermined that the first cleavage of a heavy chain constant region inan intact IgG proceeds more rapidly than the second, a sequence thatleads to a temporal accumulation of the singly cleaved species. Thissingle cleaved version of the IgG molecule is indistinguishable from itsintact parent in many ways (e.g. molecular size, antigen binding,ability to be recognized by protein A/G).

In accordance with the invention, applicants have generated reagentssuitable for the detection of proteolytic cleavage products includingF(ab′)₂ and scIgG. The reagents of the invention generated usingcleavage site analogue peptides of the invention, recognize human IgG1cleavage products but do not recognize intact IgG.

Applicants have further demonstrated that antibodies recognizing IgGcleavage products retaining antigen binding specificity can restoreeffector functions such as CDC and ADCC to the cleaved IgG.

Proteolytic Enzymes and Disease Association

The applicants demonstrated that antibody cleavage products, includingscIgGs, similar in size to those generated with in vitro enzyme panel,are detectable in inflammatory exudates such as synovial fluid frompatients with rheumatoid arthritis. Further, scIgG can be detected inthe serum of patients with a number of diseases in which localizedproteolytic activity is a known characteristic of the pathology. ThescIgG in these disease states is at higher concentrations than inhealthy normal volunteers and is also higher than in the serum ofpatients with less severely inflammatory disease.

The detection of cleaved IgG including scIgG was accomplished by thegeneration of affinity-purified polyclonal antibodies (rabbit) thatspecifically bind to newly exposed epitopes in the cleaved heavy chainat or around the hinge disulfides, but do not react with the intact,non-cleaved IgG molecule. Confirmatory support for the detection ofscIgG in serum is its prolonged circulating lifespan similar to intactIgG. The ability to detect scIgG in the bodily fluids, interstitialfluid, or blood of diseased individuals is a potentially novel biomarkerstrategy. It will be understood that other species of antibody besidesrabbit (such as mouse, rat, and camel) may be used and monoclonalantibodies produced, for example, by cloning of an antibody gene codingfor a specified antibody binding region sequence which polyclonal ormonoclonal antibody retains the ability to bind human IgG1 cleavageproducts but that do not recognize intact IgG are encompassed asreagents of the invention. Other methods of producing antibodies, e.g.by selection from antibody domain libraries, are well known to thoseskilled in the art and may be used as a source of the antibodies of theinvention.

Antibody Reagents

The antibodies of this invention can be prepared in several ways wellknown in the art using criteria and immunogens designed by applicants toraise or select antibodies useful in the practice of the invention.

In one aspect, the antibodies are conveniently obtained from hybridomasprepared by immunizing an animal with the observed cleavage fragments orcleavage site analogue peptides derived therefrom. Thus, the antibodiescan be obtained by immunizing animals or screening antibody librarieswith antibody cleavage fragments including F(ab′)₂ and scIgG, orN-terminal truncations or structural analogs thereof. In one embodiment,the peptides used for generating the antibodies are selected from the14-mer peptides fragments of IgG1 shown in SEQ ID NO: 5-11, where theC-terminal residue of the polypeptide or peptide represents the residueupstream (N-terminal side) of the cleavage site as shown in Table 1 ofthe residue cleavage pairs. Fragments comprising the hinge motif, e.g.-T-C-P-P-C- of IgG1 (residues 7-11 of SEQ ID NO: 1), will be multimericdue to disulfide bond formation, unless the cysteine residues (C) havebeen replaced with e.g. alanine (A) or serine (S) residues therebycreating a form of chemical homolog of the cleavage peptide.

In a specific embodiment, the antibody is generated using an 8-merpeptide (eight contiguous amino acids) corresponding to the sequence ofamino acids on the amino terminal side of the MMP-3 cleavage site(TCPPCPAP, residues 7-14 of SEQ ID NO: 1), or extended peptidescorresponding to the glutamyl endopeptidase site (TCPPCPAPE, residues7-15 of SEQ ID NO: 1); or the IdeS site (TCPPCPAPELLG, residues 7-18 ofSEQ ID NO: 1). When used as immunogens, the peptides can conveniently becovalently attached to keyhole limpet hemocyanin (KLH) via theN-terminus or through an added linker residue or peptide.

The antibodies can thus be obtained using any of the hybridomatechniques well known in the art, see, e.g., Ausubel, et al., ed.,Current Protocols in Molecular Biology, John Wiley & Sons, Inc., NY,N.Y. (1987-2001); Sambrook, et al., Molecular Cloning: A LaboratoryManual, 2^(nd) Edition, Cold Spring Harbor, N.Y. (1989); Harlow andLane, antibodies, a Laboratory Manual, Cold Spring Harbor, N.Y. (1989);Colligan, et al., eds., Current Protocols in Immunology, John Wiley &Sons, Inc., NY (1994-2001); Colligan et al., Current Protocols inProtein Science, John Wiley & Sons, NY, N.Y., (1997-2001), each entirelyincorporated herein by reference. An antibody of the invention caninclude or be derived from any mammal, such as but not limited to ahuman, a mouse, a rabbit, a rat, a rodent, a primate, or any combinationthereof and includes isolated human, primate, rodent, mammalian,chimeric, humanized and/or CDR-grafted anti-integrin antibodies,immunoglobulins, cleavage products and other specified portions andvariants thereof.

Phage-displayed antibody libraries may also be used to identify novelbinding domains with the desired specificity to scIgG and other antibodyfragments.

In raising or selecting antibodies or other binders useful in thepresent invention, the specific reagents used for this purpose are afurther aspect of the invention. The specific immunogens or testreagents developed for this purpose are characterized as comprisingresidues around the hinge core of the IgG1, including but not limited tothe residues SCDKTHTCPP CPAPELLGGP SVFLFP (SEQ ID NO: 1) as shown inFIG. 3. Hinge regions of other human isotype antibodies that produceantibody fragments upon contact with proteolytic enzymes may also serveas sources of peptides for the purposes of creating, selecting ortesting antibodies or other binding molecules to enzymatic cleavageproducts. An analogous region of the human IgG4 heavy chain includesresidues TCNVDHKPSN TKVDKRVESK YGPPCPSCPA PEFLGGPSVF LF (SEQ ID NO: 2)and for IgG2 and IgG3 as shown in SEQ ID NOS: 3 and 4, respectively. Ineach case, the peptides consist of at least 5 contiguous amino acidsselected from the human IgG hinge region sequences of SEQ ID NO: 1, 2,3, or 4 that are on the amino terminal side of a protease cleavage site.In one aspect, the specific immunogen or peptide used for generating theantibodies comprise at least the hinge core of the IgG1, defined as theresidues -C-P-P-C- or a analogue wherein the cysteine residues arereplaced with serine residues. In a specific embodiment, the peptide isa 12-mer peptide analogue of the human IgG1 lower hinge and adjoiningCH2 domain having the sequence TCPPCPAPELLG (residues 7-18 of SEQ ID NO:1).

A general method for creating peptide fragments useful in generating,selecting or testing antibodies or other binding molecules toproteolytic cleavage products is to a) identify the N-terminal residueof a pair of residues of an antibody heavy chain cleaved by a proteasesuch as those exemplified by specific proteases in Example 1 and shownin Table 1, b) define from 5-14 or more upstream residues from thatcleavage site where the N-terminal residue will become the C-terminus ofthe defined sequence and c) produce the peptide in sufficient amountsfor the desired purpose(s). Optionally, any cysteine residues can besubstituted with serine or alanine or other amino acid where no reactiveside groups are present or reactive side group has been irreversible orreversible blocked. Peptides such as those described are those selectedfrom SEQ ID NO: 5-11 or N-terminal truncations thereof. The peptides maybe labeled, conjugated or cross-linked or used in admixture one withanother or with adjuvants for the purposes of testing binding or asimmunogens or panning targets for use e.g. in selecting binders from aphage display library.

The present invention further provides, in one aspect, isolated nucleicacid molecules comprising, complementary, or hybridizing to, apolynucleotide encoding the aforementioned specific peptides orantibodies thereto, comprising at least one specified sequence, domain,portion or variant thereof. The present invention encompasses isolatednucleic acids encoding at least one isolated monoclonal antibody havingspecificity for the scIgG as described herein and a nucleic acid vectorcomprising the isolated nucleic acid, and/or a prokaryotic or eukaryotichost cell comprising the isolated nucleic acid. The host cell canoptionally be at least one selected from E. Coli, COS-1, COS-7, HEK293,BHK21, CHO, BSC-1, Hep G2, 653, SP2/0, 293, HeLa, myeloma, lymphoma,yeast, insect or plant cells, or any derivative, immortalized ortransformed cell thereof. Also provided is a method for producing atleast one antibody of the invention, comprising translating the antibodyencoding nucleic acid under conditions in vitro, in vivo or in situ,such that the peptide or antibody is expressed in detectable orrecoverable amounts.

Methods of Use Diagnostics

The reagents of the invention are useful in detecting disease pathologywhen the disease process invokes, is a result of, causes, or isotherwise associated with proteolytic activity and proteolytic enzymes,proteases. Such diseases and processes include those precipitating oraggravating, produced by, or resulting from infection, stroke, vasculardisease, myocardial infarction and several other acute and chronicinflammatory disorders. Applicants have demonstrated that oneparticularly useful biomarker of the proteolytic activity is scIgG,which is detected at increased levels in some of the aforementioneddisorders. As scIgG is generated located at the site of the pathology orpathological process or infection, scIgG provides a unique and specificmarker of such processes as a gauge of the involvement of specifictissues or cell types at the disease site.

In one embodiment of the method of the invention, a sample is obtainedfrom a subject suspected of having, having had, or having been treatedfor a disease characterized by elevated levels of proteases. The sampleis contacted with a binding agent, such as an antibody preparation,having specificity for IgG cleavage fragments known to result fromcontact between the disease stimulated protease and a population ofserum IgG.

The method of the invention can be used to assess whether patientspreviously diagnosed with a disease or condition are at risk foradvanced disease (e.g. cancer metastases, aggressive tumor growth,persistent infection, etc.).

In some cases, for example in the cancer patient, the detection of scIgGmay be useful to indicate advanced disease progression involvingmetastatic spread which is known to involve elaboration of proteolyticenzymes, especially MMPs. In some aspects, neoplastic disease sharesthese mechanisms generally with inflammatory processes, tissue repair,and healing (Coussens, L. M. and Werb, Z. 2002. Nature 420 (19):860-867). Other studies have shown that, for example, lipid loweringcorrelates both with a reduction in the risk for cardiac and vascularevents, e.g. thrombosis, and with a reduction in MMPs such as MMP-2 andMMP-9 and that these enzymes are produced by atherosclerotic plaques(Deguchi, J, Maanori, A., Ching-Hsuan, T. et al. 2006 Circulation 114:555-62). Thus, the methods of the invention are particularly applicablebut not limited to patients with severe arthritic syndromes (RA,ankylosing spondylitis), certain cancers (especially inflammatory breastcancer), severe coronary arterial settings (myocardial infarction andcongestive heart failure) and other diseases like asthma. The method ofthe invention may be used to distinguish those diseases and conditionsin which the pathophysiology involves or induces protease capable ofacting upon IgG from other pathologies not characterized by enhancedelevated levels of secreted proteases or wherein the proteases do notcleave IgG.

Thus, while the method of using the reagents described herein arespecific for detection of the cleaved fragments, more specific analysisof the cleaved fragments could include an analysis of the bindingspecificity of the variable regions of the cleaved antibody. Forexample, a solid phase assay which combines antigen binding selectivitywith fragmented antibody detection could be used to determine whethercertain antigens and proteases are co-localized in a subject therebyproviding information about the nature of the tissue, disease, orpathology at the site of proteolytic activity.

Drawing blood is the most frequently practiced form of tissue samplingfrom subjects, human or animal, healthy or ill. In so far as scIgG isfound systemically, and is not restricted to the site of formation, thatis, the site of the protease activity, it is a reporter marker fordisease activity which may localized in specific compartments. One suchcompartment is the synovial fluid. Thus, blood or serum collectionprovides a convenient and feasible source for detection of early diseaseusing the reagents and methods provided by the present invention.Alternatively, sampling of local settings like RA synovial fluid, lungexudates, biopsies, and the like could also be applied to patients atany stage including diagnosis or in patients with advanced disease.Cleaved antibody fragments may be detected in such tissue samples bydirect staining (immunohistochemical methods) or in fractioned samplesderived from the samples.

Tissue samples, including blood, should be treated so as to inhibit anyresidual active proteases. Chelation of metals (e.g. EDTA) effectivelyinhibits MMPs. Iodoacetamide blocks cysteine proteases (e.g. IdeS),serine proteases can be blocked with diisopropylfluorophosphate (DFP)and similar compounds. Active proteases are present in synovial fluidand the samples should be processed accordingly. Samples may also bemaintained frozen until the time of assay. Once the samples have beenappropriately processed, the scIgG specific reagents of the inventionmay be used in any antibody-based techniques such as ELISA, bead-basedformats, RIAs, known to those skilled in the art or yet to be developed.

The anti-IgG proteolytic cleavage fragment reagents of the invention maybe packaged in a kit for research or diagnostic use and for commercialsale along with other reagents such as buffers and standards such asintact human IgG and known quantities of cleaved IgG along withinstructions for the measurement and, if desired, quantitation of IgGproteolytic cleavage fragments in tissue samples harvest from subjects.

Antibody Therapy

Antibodies of the invention immunospecific for a protease cleavage siteor fragment thereof are capable of binding the remnants of enzymaticallycleaved IgG which retain antigen binding domains, e.g. Fab, F(ab′)₂,scIgG, and thus restore the Fc-related binding characteristics andattendant effector functions by providing intact functional Fc-region.Cleaved IgGs can function as antigens due to the existence of crypticepitopes exposed after cleavage and thus can be used to generateantibodies that are specifically directed against cleavage points inboth the upper and lower hinge region of IgG1 (but do not bind to intactIgG1). These antibodies are capable of restoring antibody-dependentcellular cytotoxicity (CDC) and antibody-dependent cellular cytotoxity(ADCC) effector functions to cleaved IgGs in vitro presumably byproviding a surrogate Fc-region to the cleaved antibody.

Thus, the antibodies created by the methods taught herein or having theproperty of binding to proteolytically created antibody fragments invivo may be useful as therapeutic molecules. The anti-IgG cleavagefragment antibodies of the present invention can be used to treatpatients in which a disease characterized by disease induced proteolyticcleavage of IgG. In one aspect, the anti-IgG cleavage site fragmentantibodies may be used to restore effector functions to antibodyfragments which retain target specific binding capability.

The anti-IgG cleavage site antibody intended for therapeutic orprophylactic treatment of human disease or pathology may be prepared bythe methods described herein above using the peptides of the inventionas immunogens or selection reagents. Other binding domains specific forthe cleaved IgG hinge region fragment may also be used to restoreeffector functions so long as the binding domain is associated with anFc-domain capable of restoring the effector functions; which include CDCor ADCC, to an immunospecific IgG cleavage product. Of course,non-natural, modified or variant Fc sequences are also encompassed bythe invention for the purposes of enhancing some FcR-driven interactionsand attenuating others. Modified Fc regions are taught in, e.g. U.S.Pat. No. 6,737,056, U.S. Pat. No. 7,083,784, U.S. Pat. No. 7,317,091,U.S. Pat. No. 7,355,008, U.S. Pat. No. 7,364,731, U.S. Pat. No.7,371,826, U.S. Pat. No. 7,632,497, U.S. Pat. No. 7,670,600,US20040002587A1, WO06105338A2, WO200905849, and WO2009086320.

Thus, provided within the scope of the invention are nucleic acidsequences, vectors, and host cells for the recombinant production ofanti-IgG cleavage product antibodies or Fc-fusion proteins capable ofbinding a protease cleaved IgG and restoring effector functions.

Vaccination

Antibodies of the invention immunospecific for cleavage site specificfragments, capable of binding the remnants of enzymatically cleaved IgGwhich retain antigen binding domains, e.g. Fab, F(ab′)₂, scIgG, and thusrestoring the Fc-related binding characteristics and attendant effectorfunctions of the antibody by providing a functional Fc-region, may beinduced in a subject by immunization with a cleavage fragment peptide asdisclosed herein. The anti-IgG cleavage product antibodies can beprepared by immunizing a host animal with a protease cleavage sitespecific peptide or proteolytically cleaved IgG fragments, andrecovering the antibodies from the animals' serum. In such a method, theimmunized animal is a source of the antibodies of the invention fromwhich an antibody to be used as a reagent for a diagnostic test or,alternatively, to be used therapeutically, is prepared by methodsdescribed or known in the art. In a particular embodiment, a humansubject is immunized with a protease cleavage site specific peptide orproteolytically cleaved IgG fragments and the anti-IgG cleavage productis generated in vivo. In one embodiment, the protease cleavage sitespecific peptide immunogen is selected from the group consisting of atleast five (5) contiguous amino acids selected from the human IgG hingeregion sequences of SEQ ID NO: 1, 2, 3, or 4 that are on the aminoterminal side of a protease cleavage site such as the sequences of SEQID NOs. 5-11, N-terminal truncations and chemical homologs thereof.

The use of an cleavage site specific immunization or “vaccinationstrategy” will provide universal restoration of the inherent Fc-domainfunctions of IgGs independent of the origin of the protease (i.e. ofbacterial origin or host origin in the case of proteolytically-enrichedtumors) limited only to the specificity of the cleavage site specificantibody for the epitope formed by the residue specific cleavage withinthe IgG. An individual may be vaccinated with more than one cleavagesite peptide or analogue peptide for a broader spectrum of antibodyrestorative capabilities, if so desired. Alternatively, a patient may betreated with a cleavage site specific antibody before, during or afterbeing vaccinated to produce an cleavage site specific antibody response.In a particular embodiment, the individual is vaccinated with a diseasespecific cleavage site specific peptide or an analogue peptide before,concurrent with, or following the administration of a targeted antibodypreparation designed to treat a given disease state where the targetedantibody activity involves effector function, and the antibody issubject to cleavage by one or more IgG cleaving proteases. In thismanner, the effector function of the targeted antibody can be restoredand the effect of the antibody treatment is enhanced or restored whilethe targeting function of the antibody has not been altered. In oneembodiment, the disease being treated in a subject is characterized byelaboration of one or more IgG-cleaving proteases (see Table 1).

Methods of vaccination are well known in the art and, in particular, itis known that small antigens, or haptens, and linear peptides are moreimmunogenic when a plurality thereof are conjugated to a carriermolecule which may also be immunogenic such as keyhole limpet hemacyanin(KLH). Numerous conjugation methods are known in the art and aredescribed, for example, by G. T. Hermanson in “Bioconjugate Techniques”,Academic Press, 1996. Briefly, conjugations of a hapten to a carrier isgenerally effected by means of linkers or, more appropriatelycross-linkers, which consist of linear molecules of various lengthbearing reactive functional groups at both ends. In homobifunctionallinkers (i.e. glutaraldehyde) the two functional groups are identical:in heterobifunctional linkers, they are different. The detailedconjugation chemistries are well known. As the targeted IgG cleavagefragments retain the antigen specific binding domains associated withthe N-terminus portions of the immunoglobulins (variable region, CH1and, in some case, some of the core hinge) the antibody response shouldbe directed to the portion of the analogue peptide representing a newC-terminus at the cleavage site. Therefore, it is desirable to conjugatethe N-terminus of the analogue peptide and present a free C-terminalresidue as the immunogen.

In a vaccination method, adjuvants (for example, aluminum-containingadjuvant (Alum), Incomplete Freund's Adjuvant (IFA), Complete Freund'sAdjuvant (CFA)) can be used with the unconjugated or conjugated hingeregion analogue peptides to direct the immune response to produceantibodies (humoral or Th2-driven) and direct the binding domainsagainst the cleavage site specific fragments. CD40 agonists such as thenatural ligand gp39 can be used to stimulate the immune response. A CD40agonist that activates a CD40 receptor preferably on an antigenpresenting cell, preferably a dendritic cell is one example.

Human Vaccines

Human vaccine preparations have been developed which are safe andeffective. To enhance the immunogenicity of recombinant protein-basedvaccines, adjuvants are required. The most widely used adjuvants areinsoluble aluminium salts, generically called alum, such as boehmite andaluminium hydroxyphosphate. Alum adjuvants induce predominantly aTh2-type cytokine response (Lindblad, 2004; Raz & Spiegelberg, 1999;Valensi et al., 1994). Therefore, alternative adjuvants may be requiredfor the successful development of a peptide vaccine.

Polymeric microparticle encapsulation of antigens have been evaluated asvaccine adjuvants (Eyles et al., 2003J Drug Target 11, 509-514; Singh etal., 2004 Expert Opin Biol Ther 4, 483-491). Microparticles formed ofpoly(DL-lactide co-glycolide) (PLG) are well known in the art.

Various oil-in-water emulsions have also been developed as alternativeadjuvants to alum. The most advanced of these is a squalene oil-in-wateremulsion (MF59), which is a potent adjuvant with an acceptable safetyprofile. The influenza vaccine product called Fluad comprises MF59. Likealum, MF59 can promote antigen uptake by dendritic cells in vivo.Moreover, it has been shown that, after i.m. injection, MF59 isinternalized by APCs that migrate to the lymph node. Besides promotingantigen delivery, MF59 might also act as a local pro-inflammatoryadjuvant as it was observed to promote an influx of blood mononuclearcells after i.m. injection.

Other molecules that can be used in combination with alum, MF59, ormicroparticles include, but are not limited to; CpG to enhance Th1-typeresponses to vaccines, GM-CSF, and IL-2.

The prepared immunogen with or without admixed adjuvants or “vaccine”may be administered to the subject by any suitable route, such as butnot limited to intradermally, subcutaneously, intranasally, andintramuscularly.

Various protocols may be used for vaccination. One protocol contemplatedas one aspect of the invention is the prime-boost protocol wherein afirst vaccine composition that comprises the desired immunogen, a primevaccine composition, is administered in conjunction with a boost vaccinecomposition that comprises a corresponding immunogen that differs inform from the immunogen of the prime vaccine composition. The boostvaccine composition may be administered at the same time as the primevaccine composition or it may be administered at some time following theinitial administration of the prime vaccine composition. The prime andboost vaccine compositions may be administered via the same route orthey may be administered via different routes. If the prime and boostvaccine compositions are administered at the same time they may beadministered as part of the same formulation or as differentformulations. Both the prime vaccine composition and the boost vaccinecomposition may be administered one or several times. Thus some doses ofthe prime vaccine may be administered after the administration of a doseof the boost vaccine. It is within the skill of one with ordinary skillin the art to optimize the vaccination protocol using these and otherknown or yet to be discovered variation of routes of vaccineadministration and timing for vaccine administrations.

While having described the invention in general terms, the embodimentsof the invention will be further disclosed in the following examples.

Example 1 Cleavage Analysis of Human IGG Heavy Chain

Proteolysis of human IgG heavy chain by matrix metalloproteases,cathepsins, human neutrophil elastase (HNE), and selected pathogenenzymes such as staphylococcal glutamyl endopeptidase (V8 protease), andimmunoglobulin degrading enzyme of streptococcus (IdeS) was studied.

A purified monoclonal antibody comprising a human IgG heavy chain wascontacted with the proteases described and sampling was conducted overvarious durations of contact. Fragmentation in the samples was evaluatedusing the Agilent microfluidics “lab-on-a-chip” technology for in vitrobiosizing (Goetz H et al. Biochemical and Biophysical Methods 60;281-293, 2004).

Antibody Substrates. Monoclonal antibodies were either fully human,recombinant humanized murine antibodies or human/murine chimericantibodies possessing human constant domains and hinge regions of theIgG1kappa class/subclass and species: Mab1 is a human IgG1 which binds apathogen, Mab2 (anti-cytokine) is a human/murine chimeric IgG1 antibodypossessing human constant regions and hinge domain, and Mab3 is aCDR-grafted humanized IgG1. All of the antibodies contain a kappa lightchain.

Proteolytic Enzymes and Methods of Testing. Human pro-MMP-2, MMP-7 andpro-MMP-9 were obtained from Chemicon International (Temecula, Calif.)and were activated by incubation with 1 mM p-aminophenylmercuric acetate(APMA; CalBiochem, San Diego, Calif.) for 16 hr at 37° C. prior to use(Marcy et al., 1991). Recombinant human active MMP-12 was obtained fromR&D Systems. Recombinant MMP-1 was a generous gift from Dr. HideakiNagase. Human pro-MMP-3 was transiently expressed in HEK cells with ahistidine tag in place of the hinge and hemopexin domains. The pro-MMP-3variant was activated by incubation at 55° C. for 25 minutes asdescribed (Koklitis et al., 1991). Cathepsins B, D, G, S and proteinase3 were obtained from Athens Research & Technology (Athens, Ga.). Thecoagulation enzymes thrombin, F.Xa, F.IXa, F.XIIa and kallekrein, aswell as plasmin and plasminogen, were purchased from Enzyme ResearchLaboratories (South Bend, Ind.). Tissue plasminogen activator (Activase)was a product of Genentech (South San Francisco, Calif.). Streptokinaseand activated protein C were obtained from Sigma (St. Louis, Mo.).Staphylokinase was obtained from Affinity BioReagents (Golden, Colo.).Staph. aureus V8 glutamyl endopeptidase I was obtained from PierceBiotechnology (Rockville, Ill.). Recombinant immunoglobulin degradingenzyme of Streptococcus pyogenes (IdeS) was provided by Dr. Lars Bjorckof the University of Lund (Lund, Sweden).

Proteinase digestions of purified IgGs were carried out at pH 7.5 inphosphate-buffered saline (PBS) or, for the metalloproteinases, inTris-buffered saline buffer at 37° C. Calcium chloride was included inthe metalloproteinase reactions at 1 mM for MMP-12 and 10 mM for MMP-3;otherwise no additives were used. Antibody concentrations were typically1 or 2 mg/mL and reactions were initiated by addition of enzyme to a 1%(w/w) ratio to IgG. Aliquots (10-20 μL) were removed at indicated timesand the reactions were stopped either by adjustment to 20 mM EDTA(metalloproteinase incubations) or to 1 mM iodoacetamide (cysteineproteinases) or by rapid freezing.

The major proteolytic cleavage positions in the IgG1 hinge wereidentified for enzyme-generated fragments by N-terminal sequencing ofthe purified Fc fragment (MMP-3 and MMP-12) and/or high resolution massspectrometric analyses of the purified Fab (neutrophil elastase,plasmin) and F(ab′)₂ (cathepsin G, glutamyl endopeptidase and IdeS)fragments. Fragmentation was evaluated using the Agilent microfluidics“lab-on-a-chip” technology.

Results. A list of proteinases that were examined and the results of theanalysis of the primary products of proteolytic cleavage of human IgG1is presented in Table 1. Several enzymes did not fragment IgG1 under theconditions used. Among the active proteinases, relative specificactivities under the conditions described were: IdeS>MMP-12>MMP-3,glutamyl endopeptidase>neutrophil elastase>cathepsin G, plasmin>MMP-7.

FIG. 2 depicts biosizing analyses of IgG before and during proteolyticenzyme treatment. MMP-3, glutamyl endopeptidase I and IdeS were eachobserved to cleave IgG1 in a stepwise fashion (FIGS. 2A, 2B and 2C,respectively). In each case, an early intermediate of approximately135,000 Da was generated which was subsequently converted to a speciesof approximately 100,000 Da. A fragment of approximately 35 kDa,presumably the Fc-derived monomer of the CH2-CH3 domains, was alsoformed during these reactions. The molecular weight (35 kDa) gauged bygel migration is larger than that predicted by the heavy chain fragmentamino acid sequence which would be 211 to 215 residues (between residue232 and 237 to the 447^(th) residue at the C-terminus of the heavychain) but consistent with the fragment containing the glycosylationsite in the CH2 domain. The disappearance of intact IgG (160,000 Da)occurred over a period of several hours with MMP-3 and glutamylendopeptidase I, and within a minute or less with IdeS under theseconditions. All digestions were carried out under comparable conditionsas described.

The 135 kDa intermediate was found to result from a single proteolyticcleavage in one of the heavy chains in the lower hinge domain. Undernon-denaturing conditions, the intermediate is indistinguishable fromintact IgG in certain physical properties, such as migration in sizeexclusion chromatography (data not shown). However in SDS gels, and thepresent micro capillary electrophoresis system, the cleavage fragment ofthe Fc region (CH2-CH3 domains of the heavy chain) separates from therest of the structure to reveal the reduced size intermediate (135 kDa).The size of this species is consistent with a singly cleaved IgG asreported by Gearing (2002 supra). Extended incubation of IgG1 with anyof the three enzymes resulted in conversion of the scIgG intermediate tothe F(ab′)₂ fragment and Fc.

Among the enzymes exhibiting the ability to cleave IgG1 of the differentmonoclonal IgG1-based substrates tested, was a consistent finding thatthe initial cleavage to the single-cleaved intermediate was relativelyrapid, and extended times were required for the second cleavage toF(ab′)₂ to occur. Also shown in FIG. 2D is a digest of Mab1 with humanneutrophil elastase (HNE). HNE differed from the three enzymes above inthat it cleaved IgG in the upper hinge to yield Fab fragment and acorresponding disulfide-linked Fc dimer.

The major proteolytic cleavage positions in the IgG1 hinge wereidentified for the purified Fc fragment (MMP-3 and MMP-12) and/or highresolution mass spectrometric analyses of the purified Fab (neutrophilelastase, plasmin) and F(ab′)₂ (cathepsin G, glutamyl endopeptidase andIdeS) fragments. The amino acid sequence of the human IgG1 hinge regionis presented in FIG. 3, with the identified positions of enzymaticcleavages indicated. Extended digestion with proteinases that cleaved inthe upper hinge yielded two Fab fragments; enzymes that cleaved in thelower hinge (below the core hinge disulfide bonds) yielded F(ab′)₂s.

The dominant sites of enzymatic cleavage was identified or confirmed foreach enzyme including human MMP-3 and -12, human cathepsin G, human HNE,staphylococcal glutamyl endopeptidase I and streptococcal IdeS based onmass and an analysis of the mass of the F(ab′)₂ fragment or theN-terminus of the Fc fragment, respectively (Table 1). Secondarycleavage sites were observed in some cases during extended incubations(e.g. cathepsin G and HNE), and it was uncertain if these arealternative cleavage sites for the indicated proteinase or the result ofminor, protease contaminants in these enzyme preparations. The MMP-12and HNE cleavage sites in IgG have not been previously reported. Forother proteases, the identified major IgG cleavage positions agreed withpreviously reported results (Chuba, 1994; Diemel et al., 2005; Gearinget al., 2002; Vincents et al., 2004; Yamaguchi et al., 1995).

The cleavage positions differ slightly among the enzymes; withproteolysis occurring after proline-232, glutamic acid-233 andglycine-236 for MMP-3, V8 and IdeS, respectively. These minordifferences in cleavage position are not large enough to impact theapparent molecular weight as detectable using the micro-capillaryelectrophoretic biosizing system (Agilent Technologies). Longerincubation times with MMP-3, V8 and IdeS allow the complete conversionto F(ab′)₂ fragments. The digestion of IgG1 by HNE differs from theother proteases as it cleaves before the core hinge disulfides(cysteines 226 and 229) between threonine-223 and histidine-224 to yielda Fab product and disulfide linked Fc (see FIG. 2D).

The cleavage sites are based on EU numbering and relate to the residuesshown in FIG. 3 and SEQ ID NO: 1 which encompasses from Ser²¹⁹ throughPhe²⁴³ of a human IgG1 class antibody. Several proteinases cleaved IgG1below the hinge domain, and yielded F(ab′)₂ fragments of slightlydifferent lengths (spanning Ala²³¹ to Gly²³⁷). Many of the IgG-degradingproteinases characterized in this study have been reported to beexpressed, or to be abundant, at sites of inflammation (HNE, cathepsinG, MMP-12), in the tumor or wound-healing environment (MMP-2, MMP-3,MMP-7, MMP-9, plasmin), and at sites of infection (glutamylendopeptidase, IdeS) (Dollery et al., 2003; Kilian et al., 1996;Rooijakkers et al., 2005; Schönbeck et al., 1999; Shapiro, 1999; Sukhovaet al., 1998; van Kempen et al., 2006; Vincents et al., 2004)). For manycases, it is unlikely that the extracellular expression of specificproteinases is primarily directed toward host IgG; rather, theirelaboration is associated with the physiology of disease (e.g. matrixmetalloproteinases in the tumor environment). Nevertheless, these invitro, purified enzyme/monoclonal antibody degradation studies indicatedthat human IgGs are not resistant to a number of proteinases withpotential relevance to human disease.

For enzymes that converted IgG1 to F(ab′)₂ (the majority), the cleavageswere highly specific and self limiting (unlike pepsin digestion thatreduces the Fc domain to small peptides). With the exception of IdeS,the rates of IgG1 cleavage with most of these extracellular proteinaseswere generally slower than that seen with pepsin under its optimalconditions (e.g. pH 4.0). Proteolytic fragmentation to F(ab′)₂ proceededvia single-cleaved intermediates in a two-step process. Thesingle-cleaved intermediate of IgG1 was previously proposed as apossible intermediate during digestion of IgGs with MMP-3 (Gearing etal., 2002) and with IdeS (Vincents et al., 2004). In the presentstudies, it was consistently observed that the first cleavage to thesingle-cleaved intermediate occurred relatively rapidly compared to thesecond, slower cleavage that yields F(ab′)₂. The studies reported herefocused on IgG1 because it is the predominant isotype of IgG in humancirculation. A limited number of other human isotype experiments werecarried out to determine relative susceptibilities to MMP-3 and IdeS. Inthese it was observed that IgG4 was comparable in susceptibility toIgG1, whereas IgG2 and IgG3 were more resistant under these conditions(data not shown). Comparable investigations of IgA, IgM, IgE, IgDdegradation were not done.

Proteolytic cleavage information is summarized in Table 1, where“Coagulation proteinases” included F.XIIa, FIXa, F.Xa, thrombin andactivated protein C; plasmin was plasminogen co-incubated withplasminogen activators; tPA, streptokinase and staphylokinase;“plasminogen activators alone” are without plasminogen; and the MMPswere recombinant proteinases obtained either as the active form or thepro-enzyme as detailed in the Materials; and “None” denotes nodetectable cleavage in 24 hours. Except where indicated all enzymeswhere human. The residue designations are for the EU numbering systemfor the IgG1 antibody heavy chain where the 25 residues of SEQ ID NO: 1corresponds to residues 219 through 243 of the complete mature heavychain.

TABLE 1 Disease Proteinase Association Cleaved Major Enzyme Source Type(Ref) Site Product Cathepsin G Human Serine Emphysema, Glu²³³- F(ab′)₂ +Neutrophil endopeptidase IPF, RA (2, 3) leu²³⁴ Fc granules Cathepsin BHuman Serine None Neutrophil endopeptidase granules Cathepsin D HumanSerine None Neutrophil endopeptidase granules Neutrophil Human SerineAmyloidosis, lung Thr²²³- Fab + Fc elastase (HNE, Neutrophilendopeptidase emphysema, cystic his²²⁴ leukocyte granules fibrosis,ARDS, elastase, PMN neutrophils RA, tumor invasion elastase) (2, 3)Pancreatic Pancreatititis elastase (3) Proteinase 3 Human Serine None(myeloblastin) Neutrophil endopeptidase granules Tryptase Human SerineAnaphylaxis, None Neutrophil endopeptidase fibrosis (2) granules mastcells Chymase Human Serine Inflammation, None Neutrophil endopeptidasecardiovascular granules diseases (2, 3) mast cells Kallekrein HumanSerine None Neutrophil endopeptidase granules Coagulation Human SerineNone proteinases Neutrophil endopeptidase granules Plasmin Human SerineCell migration Lys²²³- Fab + Fc (fibrinolysin) Neutrophil endopeptidase(e.g. tumors)(2) thr²²⁴ granules Streptococcal infection (6) PlasminogenHuman Serine None activators Neutrophil endopeptidase alone granulesInterstitial Human Metalloendo RA, OA, IBD, None collagenase(fibroblasts, peptidase IPF, aneurysms (MMP-1) chondrocytes, (1)Stromelysin Human Metalloendo RA, OA, Pro²³²- F(ab′)₂ + (MMP-3)(fibroblasts, peptidase atherosclerotic glu²³³ Fc chondrocytes, plaque,Crohn's fibroblasts, disease, colitis, chondrocytes, some tumors (1, 4)osteoclasts, macrophages Matrilysin Human Metalloendo Invasive tumorsLeu²³⁴- F(ab′)₂ + (MMP-7) (fibroblasts, peptidase (1, 4) leu²³⁵ Fcchondrocytes, glandular epithelial cells Collagenase 2 HumanInflammation, None (MMP-8) (fibroblasts, RA, OA (1, 4) chondrocytes,neutrophils Macrophage Human Metalloendo Inflammation, Pro²³²- F(ab′)₂ +metalloelastase (fibroblasts, peptidase tissue destruction glu²³³ Fc(MMP-12) chondrocytes, when over-expressed, macrophages aneurysms,atherosclerotic plaque (1) Cathepsin S Human Cysteine None (fibroblasts,endopeptidase chondrocytes, Glutamyl Staph. aureus Serine Staph. AureusGlu²³³- F(ab′)₂ + endopeptidase endopeptidase infection (2) leu²³⁴ Fc I(Glu V8 protease) Immunoglobulin Strep. Pyogenes Serine Strep. PyogenesGly²³⁶- F(ab′)₂ + degrading endopeptidase infection (5) gly²³⁷ Fc Enzymeof Streptococcus (IdeS)

-   Barrett A. J., Rawlings N. D. and Woessner J. F. (Eds.), Handbook of    Proteolytic Enzymes Vol. 1, Elsevier, Amsterdam, 2004.-   Barrett A. J., Rawlings N. D. and Woessner J. F. (Eds.), Handbook of    Proteolytic Enzymes Vol. 2, Elsevier, Amsterdam, 2004.-   Powers, J C. “Proteolytic Enzymes and Disease Treatment” 1982. In:    Feeney and Whitaker (eds). Modification of Proteins: Food,    Nutritional, and Pharmacological Aspects. Advances in Chemistry    Series 198. ACS, Washington, D.C. 1982 pp 347-367.-   Tchetverikov I., Ronday H. K., van El B., Kiers G. H., Verzijl N.,    TeKoppele J. M., Huizing a T. W. J., DeGroot J. and Hannemaaijer    R., 2004. MMP Profile in paired serum and synovial fluid samples of    patients with rheumatoid arthritis. Ann. Rheum. Dis. 63, 881-883.-   Vincents B., von Pawel-Rammingen U., Björck L. and Abrahamson    M., 2004. Enzymatic characterization of the streptococcal    endopeptidase, IdeS, reveals that it is a cysteine protease with    strict specificity for IgG cleavage due to exosite binding.    Biochemistry 43, 15540-15549.-   Sun H., Ringdahl U., Homeister J. W., Fay W. P., Engleberg N. C.,    Yang A. Y., Rozek L. S., Wang X., Sjobring U., Ginsburg D., 2004.    Plasminogen is a critical host pathogenicity factor for group A    streptococcal infection. Science. 305, 1283-1286.

Example 2 Cleavage of IGG in an Inflammatory Exudate

Inflammatory exudates and other such fluids are expected to possessproteolytic enzymes associated with the inflammation and wound healing.For this purpose, samples of wound fluid were obtained from Ethicon Inc.

First, an antibody substrate, which comprises human heavy chain constantdomains was randomly biotinylated. Ten microL of the biotinylatedsubstrate antibody was added to 190 microL of the wound fluid andincubated at 37° C. for 8-24 hours. At specified times, samples wereremoved. The starting IgG and samples from the various times wereapplied in separate wells to a 4-12% Bis-Tris gel and subjected to SDSPAGE. The separated bands were transferred to a nitrocellulose membraneand, following blocking with 0.1M Tris buffered saline containing 0.1%Tween 20 and 10% blocking grade milk (“Blotto”), the blot was developedusing AVIDIN-D-horseradish peroxidase reagent followed by TMB (membrane)substrate.

As evidenced by the gel image shown in FIG. 4, there was a loss ofintact IgG by 8 hr and the appearance of bands similar in size to theF(ab′)2 and Fab standards. The results of this experiment indicate thatproteolysis of IgG by enzymes in an inflammatory fluid occurs over aseveral hour period and yields fragments that correspond with fragmentsproduced by in vitro proteolysis with purified enzymes.

Example 3 Preparation of Reagent

The determination of the presence of host (patient) antibody fragmentsproduced by endogenous proteases requires a reagent which selectivelybinds to the cleaved IgG but not intact IgG. Both identification of thecleaved component and a quantitative difference between fragment contentin samples from patients with disease as compared to the normalpopulation should be able to be assessed using the reagent.

The detection of unknown, but likely small amounts of IgG fragments insolutions containing relatively high concentrations of intact IgG isdifficult. Although scIgG has been noted as a possible IgG cleavagefragment (Gearing 2002 supra), quantitation in human samples has notbeen previously performed. For this purpose, reagents with the necessaryspecificity were generated in rabbits having with a high degree ofspecificity for cleaved but not intact IgG.

Three conjugated, and progressively longer single-chain peptide analogsof the human IgG1 hinge region were used for immunization (at InvitrogenCorporation). An 8-mer peptide corresponding to the sequence of aminoacids on the amino terminal side of the MMP-3 cleavage site wascovalently attached to keyhole limpet hemocyanin (KLH) via theN-terminus (TCPPCPAP, residues 7-14 of SEQ ID NO: 1). Extended peptidescorresponding to the glutamyl endopeptidase site (TCPPCPAPE, residues7-15 of SEQ ID NO: 1) and the IdeS site (TCPPCPAPELLG, residues 7-18 ofSEQ ID NO: 1) were separately prepared as immunogens. New Zealandrabbits (two per immunogen) were immunized by subcutaneous injection of0.2 mg conjugated peptide in complete Freund's adjuvant and re-boostedthree additional times with 0.1 mg antigen in incomplete Freund'sadjuvant on days 14, 42 and 56. Serum was collected at 4, 8 and 10 weeksand pooled per immunogen for antibody purification. The immune titerswere monitored by an ELISA based on solid phase antigen peptide.

Affinity purification of antibodies employed the respective peptideantigens immobilized on an activated support. The antiserum from the tworabbits immunized with the same antigen was pooled and passed throughthe antigen column after which the column was extensively washed.Specific antibodies were eluted as low affinity and high affinity poolsusing 3M KSCN and 0.1M glycine, pH 2.5, respectively. The two poolsyielded indistinguishable binding characteristics and were usedinterchangeably and/or pooled. The three separately eluted pools ofbound antibodies were next subjected to a second affinity adsorptionstep, this time on a column containing an intact antibody comprisinghuman IgG1 heavy chain constant regions (Mab3). The intent of the secondaffinity chromatography step was to remove undesirable antibodies thatmight recognize intact IgG. However, little or no rabbit antibody wasadsorbed to the IgG column suggesting that the population of antibodieswas reactive only with the “cleaved” sequence with its exposed carboxyterminus.

The individual affinity-purified rabbit anti-peptide antibodies weretested for their ability to bind to enzymatically-generated fragments ofhuman IgG as well as intact IgG by ELISA (FIG. 5). The purifiedantibodies from the rabbits immunized with KLH conjugated to residues7-14 of SEQ ID NO: 1 (the MMP-3 site analogue ending in PAP) did notbind intact IgG and were highly specific for scIgG and F(ab′)₂ producedby digestion of IgG with MMP-3. This antibody preparation showed minimalreactivity to scIgG and F(ab′)₂ produced with V8 protease or IdeS. Incontrast, the antibodies obtained from rabbits immunized with theV8-cleavage site specific peptide analogue (residues 7-15 of SEQ ID NO:1 ending in APE) and the IdeS-cleavage site specific peptide analogue(residues 7-18 of SEQ ID NO: 1 ending in LLG) showed a cross-reactivebinding profile for scIgGs and F(ab′)₂ produced by either of these twoenzymes. However, these preparations showed minimal reactivity for theMMP-3 digested products. None of the antibody preparations bound tointact IgG and none of the antibody preparations was comparably reactivewith fragments, including F(ab′)_(z) and scIgG, produced by threedifferent enzymes as shown in FIG. 6.

The intended use of the cleavage site specific reagent is the detectionof scIgGs and F(ab′)₂ (and other potential fragments) that are producedin complex in vivo settings by enzymes present in disease specifictissues or produced by disease specific cell types or cell populations,e.g. infiltrating macrophages or neutrophils. For optimal coverage ofpotential IgG fragments, it was considered preferable to have as broad aprofile of cleavage site recognition as possible. For this reason, amixture of each of the three rabbit antibody pools was prepared at 0.33mg/mL of each component (total=1 mg/mL) for use in subsequent Westernblotting and serum-based ELISA tests. This pooled reagent is referred toas RAH-1.

Example 4 Single Chain Cleaved Immuoglobulin Assay

The novel assay employed for detecting scIgG in serum using, as acapture reagent, the RAH-1 capable of binding cleaved human IgG but notintact human IgG is described in detail as follows.

Using a Chemiluminescence ELISA, regions of a Nunc Chemiluminescence96-well plates were coated with RAH-1 at 10 mg/ml in PBS. The rest ofthe plate was left un-coated (1×PBS alone). The plates were incubated at4° C. over night. Plates were washed and 200 microlmicroL/well ofChemicon International's ChemiBLOCKER (C# 2160) was added to the platesand incubated at 37° C. for 30 minutes. The blocking buffer wasaspirated from the wells and the standards and samples were added to theplate. The standard Mab3, scIgG digested with V8, was added in duplicatestarting at 50 mg/ml in PBS containing 1% Casein and 3% BSA using serialfour-fold dilutions. The disease serum samples were added at a 1:50dilution in the same buffer. Plates were washed and a 1:6000 dilution ofJackson Immuno Research's HRP conjugated AffiniPure F(ab′)₂ FragmentDonkey anti-human IgG (H+L) which has minimal cross reactivity tovarious animals including rabbit was added to all wells. This was addedin a dilution of PBS with 1% Casein and 3% BSA and incubated at 37° C.for 1 hour. The plates were washed thoroughly and 100 ml/well of HRPsubstrate (Roche's BM Chemiluminescence POD, 582 950) was added secondsbefore plate was read on the luminescent reader.

The average luminescence from the 0 ng/ml scIgG wells on the standardcurve was subtracted from all wells that were exposed to the RAH-1 coat.This subtraction controls for any non-specific reactivity of thesecondary with the RAH-1. Then, the value for each donor on non-RAHcoated wells was subtracted from the previously-adjusted value of theRAH coated wells. This accounts for any non-specific reactivity in theserum to the plate.

Example 5 Use of Reagent to Detect Disease Associated ProteolyticActivity

The RAH-1 reagent was tested for its ability to detect IgG fragments inanother inflammatory fluid, the synovial fluid of a patient withrheumatoid arthritis (RA).

A collection of synovial fluid samples from RA patients were purchasedcommercially from Bioreclamation. Samples were diluted 1:5 in LDS samplebuffer and 10 microL of each sample loaded onto a 4-12% Bis-Tris gel. Asa control for the reactivity of RAH-1, intact IgG (Mab3), or proteasedigested IgG (partial digests of Mab3 with MMP-3, glutamyl endopeptidaseand IdeS) was loaded onto the gel as well. Following SDS-PAGE, the gelwas transferred to nitrocellulose membrane and blocked with Blotto. Themembrane was then incubated with a 1:2,500 dilution of the RAH-1 inblotto, washed with 0.1M tris buffered saline, pH 7.5 containing 0.1%Tween 20 and incubated with a 1:5,000 dilution of goat anti-rabbit IgG(H&L) horseradish peroxidase conjugate. The blot was then developedusing TMB membrane. As shown in FIG. 7, the RAH-1 preparation did notreact with the intact IgG, but detected scIgG, F(ab′)₂ possibly Fab′from all 3 protease digests. For all five synovial fluid samples from RApatients, a band was detected at the approximate size of scIgG, F(ab′)₂and Fab′, suggesting that these proteolytic fragments were presentwithin the synovial fluid from individuals with RA.

Example 6 Use of Reagent to Monitor Disease

Blood plasma or serum is a more convenient for biomarker testing thanbiological fluids or tissue extracts, such as synovial fluid. However,the advantage of synovial fluid is that it is a self-contained and localenvironment in which the proteases are active and in which the IgGfragments might be expected to accumulate as described in Example 2.Nevertheless, the ease and prevalence of serum for testing makes it aconsiderably more likely sample tissue for biomarkers, including IgGbreakdown products.

Before initiating testing for IgG fragments in different types andsources of serum, it was desirable to establish which if any of theproteolyzed IgG fragments would circulate for a sufficient period toallow its accumulation and quantification. To answer this question, acomparative pharmacokinetic study was designed. The following PKexperiment in mice was modeled on several similar previously reportedstudies in which human IgGs generally exhibit terminal half-lives of10-20 days.

Fractionated proteolysis products, Mab2 IgG1, and the scIgG and F(ab′)₂generated with MMP-3, were prepared as follows. A 20 milligram quantityof Mab2 IgG was digested with heat-activated MMP-3 as described inExample 1. The digestion was initiated by addition of enzyme to a 4mg/mL solution of Mab2 in tris-buffered saline containing 10 mM CaCl₂,pH 7.5 at 37° C. The reaction was terminated by the addition of EDTA toa final concentration of 20 mM at 48 hours. There was no residual intactIgG and the percent of scIgG, F(ab)₂ and Fc was 24%, 41% and 36%,respectively, based on Agilent bio-sizing analysis (8862-67). Theterminated digest was subjected to a two-step purification to remove theFc fragment and to separate purified scIgG and F(ab)₂. In the firststep, the digest was subjected to chromatography using proteinA-Sepharose. The unbound material from the column contained the F(ab′)₂fragment and no detectable intact IgG or scIgG. Treatment of the columnwith 0.1M sodium citrate, pH 3.5, resulted in the elution of a mixtureof Fc-containing components, the Fc fragment and scIgG. The fractionswere immediately neutralized to pH 7 by the addition of 1/10 volume of2M Tris, pH 7.0. The neutralized material was concentrated toapproximately 1 mL and dialyzed into phosphate-buffered saline, pH 7.5.The Fc fragment was separated from scIgG by size exclusionchromatography on Superdex 200 (column volume=100 mL). Two peaks elutedfrom the column, which were subsequently identified using the Agilentbiosizing technique previously described as a 135 kDa conforming to thegel band position of scIgG and a lower molecular weight peak identifiedas the Fc monomer fragment of approximately 35 kDa. The purified scIgGand F(ab′)₂ components were contacted with ActicleanEtox (0.5 mL of gelper 5 mL of each protein solution) to reduce endotoxin to AALACspecifications for allowable intravenous injection in mice (<40 EU/kg).

For the pharmacokinetic study, the equivalent milligram amount (1.9mg/kg) of intact mouse-human chimeric monoclonal antibody, Mab2 IgG1,and the scIgG and F(ab′)2 generated with MMP-3 was tested as describedbelow.

A group of twenty-one female Balb/c mice (Ace Animals) were used for thepK study. Terminal bleeds were taken via cardiac puncture from threerandomly selected mice prior to the experiment to serve as baselinecontrols. The remaining eighteen female Balb/c mice were weighed andplaced into six equal groups. Two groups were injected with intact Mab2IgG1, two groups with Mab2 scIgG1 produced with MMP-3 and two groupswith Mab2 F(ab′)′)₂ produced with MMP-3. All injections were i.p. at aconstant dose volume of 10 ml/kg based on individual animal weight at0.19 mg/ml. Therefore, each animal received a 1.9 mg/kg dose at dayzero. Approximately 80 microl of blood was collected at 1 h, 24 h, 7 d,21 d, 35 d from the first of the two groups and at 5 h, 48 h, 14 d and28 d from the second group The serum samples were stored at 20° C. untiltested.

The IgG and IgG fragment concentrations of the collected serum wasquantified via enzyme-linked immunosorbent assay (ELISA). A 0.5microg/ml dilution in PBS of Jackson Immuno-research: Goat Anti-HumanIgG, F(ab′)₂ fragment specific (with minimal cross-reactivity to bovine,horse and mouse serum proteins) was used to coat Costar 3369 plates.Plates were blocked with PBS/casein/BSA. Following blocking, standardsand samples were added in a PBS/1% casein/3% BSA. Standards includedserial dilutions of the following: a murine/human IgG1, murine/humanscIgG1 MMP-3 or murine/human F(ab′)2 MMP-3 starting at 1000 ng/ml Eachtime point sample was serially diluted from 1:10 to 1:163,840 in PBS/1%casein/3% BSA. Human IgGs bound to the plates coated with anti-humancapture antibody were detected with 50 ul/well Jackson Immuno-research:Goat Anti-Human IgG (H+L) (with minimal cross-reactivity to bovine,horse and mouse serum proteins; 109-035-083) and incubated for one hourat RT. The plates were thoroughly washed and exposed to 50microlO-phenylenediamine (OPD) substrate for approximately 10 mins andstopped with 50 ul/well 3M HCL and read at 490-650 nm. The results areshown in FIG. 8.

The results of the mouse PK experiment indicate that the scIgG possessesan extended circulating lifetime, but that the F(ab′)₂ does not. Thevery rapid clearance of F(ab′)₂ in the mice is consistent with the rapiddisappearance of this fragment in humans (Roskos L K et al. Drug Dev.Res. 61: 108-120, 2004). These results point to scIgG as the mostabundant, long-lived, and useful proteolytic component of IgG forbiomarker purposes.

Example 7 Proteolytic Enzymes in Disease

In order for the scIgG to be a useful disease biomarker, it must exhibitdifferential quantity in samples obtained from patients in defineddisease categories as compared to healthy people.

A commercial source of serum from diseased individuals was identified asGenomics Collaborative (now SeraCare Life Sciences Inc.). Small volumes(300 microL) of serum from 10 different individuals within each of 8diseases were purchased. The disease categories were rheumatoidarthritis, osteoarthritis, asthma, type-1 diabetes, breast cancer, lungcancer, myocardial infarction, and congestive heart failure. Inaddition, serum from 28 age-matched and gender-matched normal healthyvolunteers were obtained from this vendor as controls.

Using the assay as described in Example 4, the samples were analyzed andthe results shown in FIG. 9. The assay, based on the selectivity of theRAH-1 reagent, demonstrated that IgG cleavage products comparable tothose generated by known specific proteases are clearly detectable andabove levels maintained in healthy or normal donors for an inflammatoryautoimmune disease, rheumatoid arthritis. In contrast, patients withosteoarthritis showed levels which were similar and in the range ofthose for the normal individual's samples.

Example 8 Modified Single Chain Cleaved IGG Assay

A solid phase assay, ELISA, using reagent RAH-1 for detection of scIgGin serum was described in Example 4. In order to optimize the detectionrange for scIgG concentrations serum samples specific changes were made.

The plates used were Immulon 4 HBX plates (VWR) coated with rabbitpolyclonal antibodies (RAH-1) at a concentration of 5 μg/mL in PBS pH7.2 (100 μL per well) by sealing and incubating the plate for 1 hour atroom temperature. Thereafter, the plate is washed 3× with PBS, 0.05%Tween (Sigma) on automatic plate washer. All samples and standards arediluted with PBS containing 1% BSA, 0.05% Tween. Anti-IgG Fc-Biotin(USBiologicalsUS Biologicals, Swampscott, Mass.) is the means ofdetection of scIgG standards or scIgG unknowns in serum dilutions.

The plate is blocked using 200 μL of SuperBlock (Pierce) for 15 minutesat room temperature (RT) with shaking and then washed plate 3× with PBS,0.05% Tween on an automatic plate washer.

The standard material; Mab1 protease digestion product, is added toduplicate wells starting at 600 ng/mL (100 μL per well, 3 folddilutions). Serum samples are diluted 1:100, 1:200, 1:400, etc. asappropriate). Samples are added in duplicate at the same time andincubated for one hour at RT on a shaker followed by 3× washing withPBS, 0.05% Tween on an automatic plate washer.

The IgG Fc Biotin dilution of 1:20,000 (dilute appropriately in assaybuffer), is added to all wells at 100 μL per well and incubated for onehour at RT on a shaker followed by 3× washing with PBS, 0.05% Tween onan automatic plate washer.

SA-HRP (Streptavidin conjugated to horseradish peroxidase, Sigma, usedat a 1:30,000 dilution in PBS, 0.05% Tween, 1% BSA) is added to allwells (100 μL per well and incubated for one hour at RT on a shakerfollowed by 3× washing with PBS, 0.05% Tween on an automatic platewasher.

Finally, 100 μL of TMB (3,3′,5,5′-Tetramethylbenzidine a peroxidasesubstrate) as provided by the manufacturer (Sigma) is added to each welland allowed to incubate for about 10 minutes for color development. Thereaction is stopped with 75 μL of 1 N H₂S04 and read plate at 450 nm.

Using the above ELISA format, the assay demonstrated greatly improvedlinearity and spike recoveries of scIgG in normal, healthy serum. Thedilution linearity of the assay was determined in two serum pools,diluted 1:100 then spiked with Mab1 at concentrations of 150 ng/mL and300 ng/mL, and further diluted to concentrations of 0, 25, 75, and 100%serum. Each sample dilution was assayed in triplicate and mean analyterecoveries were calculated. Linearity was assessed by calculation of anR² correlation coefficient from a plot of the observed (y-axis) versusexpected (x-axis) analyte recovery results for each sample pool. The R²values were: Sample 1 Low 0.9983; Sample 1 High 0.9913; Sample 2 Low0.9852; Sample 2 High 0.973; and dilution linearity was 100% for alldilutions.

Example 9 Detection of Single Cleaved IGG in Serum

Serum from RA patients was used exclusively in order to further studythe results in Example 4 where some serum samples from this group ofpatients had notably higher scIgG compared to controls.

Serum samples from 10 subjects with rheumatoid arthritis (RA) and from10 age- and gender-matched healthy individuals were obtained fromGenomics Collaborative. Using the modified assay described in Example 8,the samples were analyzed and the results shown in FIG. 10. The resultsindicated that 4 of the 10 subjects with RA demonstrated serum scIgGconcentrations >60 μg/mL. In the healthy control group, scIgGconcentrations ranged from <8.2 μg/mL to 52.7 μg/mL. The samples forthis comparison were not rigorously selected for stage of disease,treatment regimens, etc. Thus, it can be anticipated that furtherdiscrimination of healthy and disease-related serum scIgG might occur inlongitudinal analyses of patients from well-controlled and prospectivelydesigned clinical trials. However, the present assays on thesecommercial samples suggest that elevated scIgG concentrations can bedetected in patients with disease.

Example 10 Preparation of Cleavage Site Specific IGG Monoclonal Antibody

It would be desirable to produce a defined molecule, such as amonoclonal antibody, for manufacture and potential use in human patientswhich binds cleaved IgG and not intact IgG. The following procedurerepresents a method for generation of such a molecule.

A 12-mer peptide analogue of the human IgG₁ lower hinge region andadjoining CH2 domain was the immunogen: TCPPCPAPELLG (residues 7-18 ofSEQ ID NO: 1) which is a peptide analogue of the IdeS cleavage site ofhuman IgG1. The naturally occurring cysteines were replaced by alaninesto give the variant TAPPAPAPELLG (SEQ ID NO: 12). An N-terminal cysteinewas added to allow for conjugation to keyhole limpet hemocyanin (KLH) bystandard chemical methods for reaction to free sulhydryls.

New Zealand white rabbits (3) were immunized with 0.5 mg KLH peptide incomplete Freund's adjuvant using multiple subcutaneous sites (5). Theanimals were boosted with the 0.25 mg immunogen in incomplete Freund'sadjuvant at three-week intervals for a total of 4 additionalimmunizations.

The serum antibody titers to a BSA-conjugated version of the samepeptide were monitored during the course of the immunization by standardELISA methods. Animals (2) were chosen for splenectomy based on thetiter data. Rabbit hybridomas were generated from spleen-derivedlymphocytes fused with a rabbit fusion partner cells (Spieker-Polet,1995 PNAS USA 92(20):9348-9352). Cell growth was examined 2-3 weeksafter fusion in multiple plates.

Positive hybridomas were screened via ELISA on plates coated with theBSA-immunogen peptide conjugate. Multiple positive clones from eachfusion were identified. Further screening involved binding to intactIgG1 and various enzymatically-generated F(ab′)2 fragments of IgG1. Fromthese screening and counter-screening tactics, three clones (designated33-2, 91-2, and 68-6) were chosen based on strong selectivity of bindingto the immunogen peptide and to F(ab′)2 fragments with C-termini at ornear the C-terminus of the immunogen peptide and with minimal binding tointact IgG1. The positive hybridomas were subcloned and expanded.

Rabbit IgG was purified from individual cell supernatants by standardmethods including chromatography on immobilized protein A. Thespecificity of the purified rabbit IgGs for binding to peptide analogsof the human IgG1 hinge region, as well as intact IgG and purified IgGfragments created of single or doubly cleaved (F(ab′)2) cleaved withmAbs using IdeS and MMP-3 enzymes were tested in standard ELISAprotocols. Briefly, the peptides which were synthesized by standardpeptide chemistry and were N-terminally biotinylated were captured onstreptavidin-coated wells. The IgG and fragments were directly coated at10 μg/mL. Binding of rabbit mAbs was detected by well-characterized goatanti-rabbit IgG Fc-horseradish peroxidase and OPD substrate systems.

The ELISA results for rabbit mAb 91-2 are shown in FIG. 11. There was aclear selectivity of binding for lower hinge peptides terminating at anyof the residues 16-23 of SEQ ID NO: 1 (L-L-G-G-P-S-V-F). There is littleor no binding to the peptides terminating at any of the upstreamresidues corresponding to those segments of the upper hinge, core hingeor early lower hinge encompassed by 3-15 of SEQ ID NO: 1(D-K-T-H-T-C-P-P-C-P-A-P-E). There was negligible binding to the MMP-3generated F(ab′)2 fragment and scIgG fragment (in agreement with thelack of binding to the peptide analogs of the MMP-3 cleavage sitebetween residues 14 and 15 of SEQ ID NO: 1 (ending in P-A-P). Incontrast, there was substantial binding to the Ides-generated F(ab′)2fragment and scIgG which should have the C-terminal sequence(-P-A-P-E-L-L-G). Thus, the rabbit mAb binding specificity conformedwell to the immunogen to which it was elicited. Directly coated rb(rabbit) IgG was a positive control.

Complement Assay

WIL2-S cells, a lymphoblastoid B-cell line expressing CD20 (ATCCCRL-8885), were used as target cells for CDC assays. 50 μl of cells wereadded to the wells of 96-well plates for a final concentration of 8×10⁴cells per well in RPMI, 5% heat-inactivated FBS, 0.1 mM nonessentialamino acids, 1 mM sodium pyruvate, penicillin (500 U/ml), streptomycin(500 U/ml), 2 mM L-glutamine. An additional 50 μl was added to the wellswith or without antibodies of various concentrations and the plates wereincubated at room temperature for 2 hours. 50 μl of 10% rabbitcomplement (Invitrogen) was added to the wells and the plates wereincubated for 20 minutes at 37° C. All samples were performed intriplicate. The plates were centrifuged at 200 g for 3 minutes and 50 μlof supernatant was removed to separate plates and CDC was measured withlactate dehydrogenase (LDH) cytotoxicity detection kit (Roche).Absorbance was measured using a Spectra max Plus 384 (PerkinElmer). Datawere normalized to maximal cytotoxicity with Triton X-100 (SigmaAldrich) and minimal control containing only cells and complement alone.

FIG. 12 shows that the 3 rabbit cleavage site specific mAbs were able torestore complement dependent cell lysis to the target cells whentitrated in the presence of a fixed concentration of the F(ab′)2fragment of an antibody that binds CD20. The rabbit mAbs were moreeffective, and, at lower concentrations than a polyclonal rabbitcleavage site specific mAb preparation (a component of the samedetection system for serum scIgG described earlier). Intact antibody toCD20 was active, as expected, but its F(ab′)2 fragment and scIgG versionwere not active alone. The rabbit cleavage site specific mAbs were notable to direct cell lysis in the absence of cell-binding F(ab′)2fragment. These results establish that monoclonal cleavage site specificantibodies can reconstitute complement-mediated effector function tootherwise inactive proteolytic cleavage products of IgG1.

In order to test the restoration of effector functions in human system,the rabbit antibody variable domains of Mab 91-2 were cloned, fused tohuman constant domains and expressed in HEK293 cells. The resultingrabbit-chimeric Mab was designated 2095-2. The antibody specificity wasagain tested by binding to cleavage site peptides in an ELISA format andconfirmed that the highest affinity was for the peptide terminating with-P-A-P-E-L-L-G.

The specificity of binding was further examined using a Fab fragment ofthe 2095-2 antibody using a surface plasmon resonance platform(Biacore). Briefly, the Fab was immobilized to a CMS sensor chip in aBiacore 2000 at three different surface densities (8500, 1650, and 350RU) using standard NHS/EDC coupling. The running buffer contained 10 mMHEPES pH 7.4, 150 mM NaCl, and 0.01% Tween-20. Data were collected at25° C.

Three N-terminally biotinylated peptides were tested for binding of tothe immobilized Fab: WT, representing the expected sequence of a peptidefragment from a human IgG1 cleavage site after cleavage by theStreptococcus pyogenes IdeS protease; E233A, representing a variant ofhaving a single alanine substitution at the amino acid residue fourpositions upstream of the C-terminus; and L234A, a variant having asingle alanine substitution at the amino acid residue three positionsupstream from the C-terminus. The peptides were modified by substitutingserine for cysteine to make them compatible with the coupling chemistryand preserve the monomeric structure.

Peptides Wild type and E233A were tested in a 3-fold dilution seriesusing 588 nM and 2.9 uM as the highest concentration, respectively.Peptide L234A was tested at 14.7 uM as the highest concentration in a2-fold dilution series. Each peptide concentration series was tested intriplicate over the three different density Fab surfaces. Theassociation and dissociation were monitored for 1 minute. Surfaces wereregenerated with a 12 second injection of 1/500 dilution of phosphoricacid. The response data from each surface were globally fit to determinethe binding constants summarized in the table below. Each peptideinteraction fit very well to a simple 1:1 (Langmuir) model.

The association rates (k_(a) in M-1s-1)) varied by less than a factor of10, however, the dissociation rates (k_(a) in s-1) varied by more than200-fold. The calculated K_(D) in nM for the three peptides is shownbelow (Table 2).

TABLE 2 Peptide k_(a )(M-1s-1) × 10⁻⁵ k_(d) (s − 1) K_(D) WtBiotin-TSPPSPAPELLG 5.22 ± 0.04 0.00443 ± 0.02   8.5 nM (SEQ ID NO: 13)E233A Biotin-TSPPSPAPALLG 7.29 ± 0.03   0.1070 ± 0.04 146.8 nM(SEQ ID NO: 14) L234A Biotin-TSPPSPAPEALG 1.24 ± 0.01     1.03 ± 0.01 8340 nM (SEQ ID NO: 15)

These results indicate that the monoclonal antibody 2095-2 is highlyspecific for the binding to the immunogen used which is an analogue ofthe IdeS cleavage site peptide from the N-terminal (upstream) sequenceof human IgG1 and is in monomeric conformation due to the removal ofcysteine residues.

Example 11 In Vivo Model for Cleavage Site Specific Antibody

In order to test the capacity of cleavage site specific antibodies torescue cleaved IgGs in vivo, a model for bacterial infection employing a“tissue cage” (Fernandez J A, et. al. (1997) Antimicrob. AgentsChemother. 43(3):667-671) was adopted. In this system, a wiffle ball issurgically implanted subcutaneously in the dorsal cervical area. Themodel allows the infectious agents to be localized within an easilyaccessible fluid compartment, a tissue pouch, and has been used toassess the efficacy of antibiotics against bacteria.

In the present system, the rabbit wiffle fluid ball was found to containapproximately 1.5 mg/ml IgGs, in contrast to 5-10 mg/ml of IgGs reportedin rabbit serum. Our hypothesis is that infection of rabbits with theGluV8-expressing bacteria S. aureus would result in cleavage of therabbit IgGs within the wiffle ball. Furthermore, vaccination of rabbitswith a GluV8-cleaved IgG cleavage site specific peptide analogue wouldresult in robust cleavage site specific titers that would provide ameasure of protection against S. aureus.

In order for the model to provide a positive result in demonstratingthat rabbit cleavage site specific antibodies can provide some level ofprotection against S. aureus infection, four factors must be operating.First, GluV8 must be capable of cleaving rabbit IgGs. Second, rabbitsmust have either some pre-existing immune reactivity to S. aureusantigens or they must be able to generate an antibody-mediated immuneresponse against S. aureus shortly after infection as these will becomethe subject IgG. Third, the vaccination approach must yield cleavagesite specific antibodies of sufficient affinity and specificity to bindthe cleaved rabbit IgGs. Finally, animals immunized with the cleavedantibody analogues must demonstrate a measurably different response thannon-immunized animals.

We previously showed that GluV8 cleaves human IgG1 between the aminoacids E233 and L234 (WO2009/023457A1, Ryan M H, et al. (2008) MolImmunol 45(7):1837-1846) located in lower hinge region in vitro. Thesequence of the rabbit IgG lower hinge region in this region isidentical to the human IgG1 sequence except for the single amino acidchange, A231P. As the GluV8 cleavage site it was expected that theenzyme would act on rabbit IgG.

Human IgG1 ₂₂₉CPAPELLGG₂₃₆ Rabbit IgG1 ₂₂₉CPPPELLGG₂₃₆

Rabbit IgGs from the serum and from the S. aureus containing wiffle ballfluid of rabbits three days after inoculation were purified separatelyusing a Protein A reagent. The resulting preparations of rabbit IgGswere analyzed by MALDI to determine the amount of IgG cleavage. TheMALDI analysis of the rabbit serum IgGs revealed three primary peaks,corresponding to the singly-charged molecular ion of intact IgG (143,600Da), the doubly-charged molecular ion of intact IgG (71,700 Da), andrabbit albumin (65,800 Da). In contrast, the MADLI analysis of wiffleball rabbit IgGs contained the singly-charged molecular ion of an Fcfragment (52,800 Da), the doubly-charged molecular ion of an Fc fragment(25,500 Da), and a small peak corresponding to the singly-chargedmolecular ion of intact IgG (143,700 Da). These results indicated thatrabbit IgGs purified from S. aureus containing wiffle ball fluidcontained cleaved IgGs, whereas rabbit IgGs purified from the serumcontained intact IgGs with no detectable IgG cleavage products.Therefore, we concluded that rabbit IgGs in vivo, like human IgG1 invitro, are susceptible to cleavage within a microenvironment containingS. aureus.

With regard to the immune status of the study animals toward Staph.aureus, the presence of pre-existing immune reactivity in serum wastested by ELISA using two S. aureus-derived antigens. These were Staph.alpha toxin (alpha-hemolysin, H1a) and Staphylococcal Enterotoxin B (atoxin commonly associated with food poisoning). The pre-study serum fromthe six rabbits that subsequently were immunized with the hinge analoguepeptide, and the pre-inoculation serum from 6 non-immunized controlrabbits were tested at 1:50, 1:200 and 1:800 dilutions for binding tothe two toxins. A positive titer was quantified as the highest dilutionat which optical density (490 nm) was two-fold or greater than thesignal obtained in the corresponding control well (non-antigen coated).In addition, a human integrin and chicken egg albumin were tested aspotential negative controls since it was unlikely that rabbits wouldhave been exposed to such proteins. The results are tabulated below(Table 3).

TABLE 3 Incidence of Antigen positive reactivity Titers (n) Staph alphatoxin 8/12 1:50 (2), 1:200 (1), >1:800 (5) Staph enterotoxin B 12/12 1:50 (3), 1:200 (3), >1:800 (6) Human integrin 1/12 1:50 (1) Chicken eggalbumn 4/12 1:50 (4) (ovalbumin)

Results

The results indicated that there was a substantial incidence ofanti-Staphylococcal toxin reactivity in the 12 study animals. In somerabbits, the titers would clearly have exceeded the maximum dilutiontested (1:800). In contrast, the incidence of immune reactivity to thehuman and chicken antigens was markedly lower and was detectable only atthe 1:50 dilution. These results supported the supposition that rabbitsare naturally exposed to S. aureus in their lifetimes and should becapable of immediate targeting of S. antigens upon inoculation, orpossess the ability to rapidly mount a recall response. These findingssuggest that a spectrum of antibodies to Staph. aureus antigens may bepresent including antibodies to cell surface components.

Example 12 Immunization

The procedure described in Example 11 verified that test subject rabbitshave had previously developed immune titers to Staph. aureus antigenswhich would provide for natural bacterial targeting antibodies. Todetermine if rabbits would generate a sufficiently specific and robustcleavage site specific antibody response after vaccination with cleavagesite peptides to protect against a bacterial challenge, the followingexperiment was performed where rabbits were immunized with aGluV8-cleavage site peptide analogue (residues 7-15 of SEQ ID NO: 1,TCPPCPAPE) conjugated to the immunogen KLH.

A peptide analogue of residues 225-233 of the human IgG1 hinge waschemically synthesized. The immunogen peptide, C-T-S-P-P-S-P-S-P-A-P-E(Cys-Thr-Ser-Pro-Pro-Ser-Pro-Ala-Pro-Glu, SEQ ID NO: 16) was designedwhich included an N-terminal Cys for linkage and an internalsubstitution of Ser for the Cys that occurs at position 226 and 229 inthe IgG to avoid oxidation and dimerization of peptides at thosepositions.

The peptide was prepared on an ABI 433A Peptide Synthesizer using 0.25mmol scale FastMoc chemistry and Fmoc-Glu(OtBu)-Wang Resin.Approximately 190 mg of crude peptide was released from the resin andwas purified via multiple injections onto two Vydac C-18 columns.Fractions were collected and analyzed by RP-HPLC and MALDI-TOF MS.Pooled fractions yielded 38 mg of lyophilized product having freecysteine by Elllman's test.

The conjugation of the peptide to keyhole limpet hemocyanin (KLH) wasaccomplished with EDC coupling chemistry(1-Ethyl-3-[3-dimethylaminopropul]carbodiimide) using the ImjectImmunogen EDC Kit (Pierce product no. 77622). 22 mg of purified peptideat 4 mg/mL in EDC conjugation buffer was combined with an equivalentmass of KLH at 10 mg/mL in water. Linkage of peptide to KLH occurredfollowing addition of EDC solution to the mixture with gentle mixing for2 hours at room temperature. All of the above steps were performedaccording to the manufacturer's directions. The conjugation mixture wasdialyzed against PBS to remove excess linkage reagents. The KLH-peptideconjugation was confirmed by sandwich immunoassay using the polyclonalrabbit cleavage site specific specific antibody preparation RAH(reactive to a cleavage site specific analogue peptide ending with thesequence C-P-P-C-P-A-P-E) as described in Example 3 and biotinylatedanti-KLH antibody as capture and detection antibodies, respectively.

Following immunization, the reactivity of rabbit serum to the peptideanalogue was tested by ELISA. Table 4 shows the titers (as thereciprocal of the dilution at which a signal was detectable), whichindicate that all of the rabbits had antibodies reactive to the cleavagesite specific analogue peptide detectable in the serum. One animal (657)had a very low level of detectable antibodies to the immunogen with a1/titer equaling 640. Cleavage site specific antibodies were alsodetected in the wiffle ball fluids of all six rabbits, with the sameanimal (657) having a low level of detectable antibodies. Therefore,five of the six rabbits demonstrated robust cleavage site specificantibody titers detectable in both the serum and wiffle ball fluids.

TABLE 4 Rabbit Serum (titer) Wiffle ball (titer) 651 12,800 3,200 65351,000 12,800 656 820,000 51,000 657 640 320 659 51,000 12,800 661205,000 12,800

In the final phase of the study, the immunized and non-immunized rabbitswere inoculated with 6.2 log 10 colony forming units (CFUs) of S. aureus(ATCC 29213) directly into the wiffle-ball compartments.

The bacterial counts and test subject viability were monitored over thecourse of two weeks for bacterial counts and survival. The data shown inFIG. 13 indicate that during the first week of the study, the averagebacterial counts for control animals were several logs higher thancleavage site specific vaccinated animals. For example, on day 2 thecontrol had 7.2 log₁₀ CFU/ml wiffle ball fluid while the immunized grouphad 5.2 log₁₀ CFU/ml wiffle ball fluid.

The differences in bacterial counts translated into a profounddifference in rabbit viability. By the end of the two week study, only40% percent of the control animals survived, while 100% of the cleavagesite specific vaccinated animals were viable (FIG. 14).

Therefore, these results supported the hypothesis that innate immunityto pathogens, when present, can be restored to an effective level by thepresent method of immunization against the byproduct of pathogenproduced proteases, presumably the cleaved but still immunoreactiveanti-Staph. aureaus IgG. This process was evidenced by not only reducingbacterial counts of inoculated animals with a highly proteolyticbacterium, but also by the fact that the animals were rescued frommortality.

Example 13 Passive Immunization to Treat Cancer

To demonstrate the principle of restoration of effector functions by ancleavage site specific antibody to a tumor targeting Mab, a murine humantumor xenograft model, the MDA MB 231 orthotopic xenograft model in SCIDBeige mice, was used with an antibody called CNTO860 (U.S. Pat. No.7,605,235), directed against human tissue factor (CD142) previouslydemonstrated to show the ability to reduce tumor growth in the model.

The study was designed to show that proteolytic cleavage of the lowerhinge domain of the IgG1 of CNTO860 would render the antibodyineffective and evaluate if an cleavage site specific cleavage site mAbwould restore the anti-tumor efficacy of cleaved CNTO860 in theMDA-MB-231 orthotopic xenograft model in SCID Beige mice.

The intact anti-tumor antigen antibody, CNTO 860, comprises a human IgG1constant regions. A protease cleaved antibody, CNTO860, was preparedusing the bacterial protease IdeS, as described above.

The antibody preparations were diluted fresh each week and supplied at10 μg/mL in PBS for animal dosing at 0.1 mg/kg. The mAb 2095-2 (chimericcleavage site specific cleavage_(Ides)) was administered alone at sameschedule as for the 860 variants above at 1.0 mg/kg.

Immunocompromised mice (SCID Beige mice (C.B-17/IcrCrl-scid-bgBR)approximately 18-20 g in weight obtained from Charles RiverLaboratories) were anesthetized and implanted with MDA-MB-231 a humanbreast carcinoma line (ATCC #HTB-26) cells suspended at 5×10⁷ cells/mLin serum-free DMEM into the (Right axillary number 2 or 3) mammary fatpad in a volume of 50 μL as specified by an IACUC approved protocol.

Mice, eight per group, received test substances or PBS (control group)as shown in the Table 5 (below). Group 4 received CNTO 860 singlecleaved IgG dosed as specified above for mono-therapy plus mAb 2095-2administered at 1.0 mg/kg, dosed with a 2-hr delay i.p. The dosing beganon day 3 of the study and was repeated once per week.

TABLE 5 First Injection Second Injection Group (i.v., 0.2 cc/20 g)Dosage (i.p.) Dosage 1 PBS-- — — 2 CNTO860 0.1 mg/kg — 3 CNTO860 single0.1 mg/kg — cleaved IgG 4 CNTO860 single 0.1 mg/kg Cleavage site 1 mg/kgcleaved IgG specific mAb 2095-2 5 PBS — Cleavage site 1 mg/kg specificmAb 2095-2

The study was terminated when the control group tumors reach 800 mm3 involume. At termination, whole blood was collected via cardiac punctureinto prepared EDTA coated tubes from all animals. At the termination ofthe study, body weights and tumor measurements were recorded and theprimary tumors surgically removed, and weighed.

Results

The mean tumor volumes for each group of mice at specific times duringthe experiment are shown in FIG. 15. Statistically, the tumor volumes inthe CNTO860 treated group were lower compared to each of the othergroups starting at Study Day 11. The tumor volumes in the combinationCNTO860 plus mAb2095-2 group were lower than those in the PBS group fromStudy Days 18-40; lower than those in the CNTO860 scIgG alone group fromStudy Days 26-40; and lower than those in the mAb2095-2 alone group fromStudy Days 18-40. There were no other differences in tumor volume amongthe treatment groups.

The CNTO860 alone group had much smaller final tumor weights than everyother group. Additionally, the combination CNTO860 plus mAb2095-2 grouphad smaller tumors than both the PBS and mAb2095-2 alone groups. Therewere no other differences among the treatment groups in tumor weight.

These results demonstrate that passive immunization with a cleavage sitespecific antibody preparation restores anti-tumor activity where acleaved target specific antibody in present.

Example 14 Target Cell Depletion Using a Cleavage Site Specific Antibodyand Cleaved Targeting Antibody

In the following experiment, the in vivo administration of a cleavagesite specific antibody (rabbit-human chimeric mAb 2095-2 withspecificity to human IgG1 cleaved by IdeS (chimeric cleavage sitespecific cleavage_(Ides))) following administration of a single-cleavedIgG or double-cleaved IgG, (a F(ab′)₂), was investigated.

The anti-platelet integrin (α_(IIb)(β_(IIIa), also called IIb/IIIa)binding antibody, c7E3, was used as the targeting antibody for severalreasons. The anti-platelet mAb was a human IgG1 chimeric that was shownin a pilot study to result in profound platelet clearance after 24 hourswith recovery over 5 days (indicating substantial acute recognition ofthe mAb by the canine Fcγ receptors and/or complement system).Additionally, the effect was distinguishable at a dose of the intact IgG(0.05 mg/kg) that did not cause inhibition of platelet function andtherefore not likely to cause clinically relevant bleedingcomplications. Lastly, circulating platelet numbers provide a readilyquantifiable endpoint and the multiple blood samplings in thisnon-terminal study did not pose blood loss artifacts or risks foranimals of this size.

Materials and Methods

Three preparations of c7E3 were used: the intact murine-human IgG1chimeric antibody, a single cleaved and a F(ab′)₂ prepared using thebacterial enzyme IdeS.

First, the c7E3 antibody antigen binding and platelet depletionparameters were established in dogs. The results of the test infusionsof showed that 0.01 mg/kg dose (that would be calculated to be more thansufficient to drive platelet clearance in humans) was ineffective indogs at 2 and 24 hours and was indistinguishable from the saline group.The 0.05 mg/kg dose had little effect by 2 hours but at 24 hours hadresulted in >90% platelet clearance. The 0.2 mg/kg dose of c7E3 IgGresulted in profound platelet clearance at 2 hours that was thenmaintained at 24 hours. These results provided the needed information toassign the minimum dose in dogs (0.05 mg/kg) that would result insubstantial, acute platelet clearance (24 hours).

Effect on Platelet Function

c7E3 inhibits platelet aggregation by binding to platelet surfaceIIb/1113 receptors—thereby blocking the ability of fibrinogen to bind tothe receptors on activated platelets and to clump them together. Therespective inhibitory profiles of intact and single-cleaved c7E3 IgGwere tested in a platelet aggregation assay. Platelet aggregation ismeasured as an increase of light transmission through a plateletsuspension after activation with a physiological agonist. The inhibitionis compared to control aggregation to 5 μM adenosine diphosphate (ADP).The percent inhibition was calculated as: control aggregation—testaggregation×100%, divided by control aggregation.

The results indicated that there was no loss of binding/inhibition ofc7E3 to platelets after single lower hinge cleavage by the IdeSprotease.

c7E3 IgG and c7E3 IgG single-cleaved by IdeS protease were also comparedin vivo. Three groups of 5 animals received either saline control,intact c7E3 IgG (0.05 mg/kg) or c7E3 single-cleaved IgG (0.05 mg/kg).Platelet counts were monitored at baseline and at 2, 24, 48, 72 and 96hours post-administration. Limiting the study to 5 days minimized thelikelihood of anti-c7E3 immune responses that might confound theinterpretation of the results. The results are presented in FIG. 3 asthe mean platelet count±SD for each animal group at each time point. Theextent of the error bars connotes the normal variability of plateletcounts in different animals (for example, the predose counts for the 5animals in the single-cleaved IgG treatment group were 175,000, 355,000,305,000, 276,000 and 334,000 per μL, respectively). Nevertheless, themean results clearly confirmed that intact c7E3 IgG induced asubstantial decrease of platelet numbers with a nadir apparent at 24hours. The single cleaved version of c7E3 IgG at the same 0.05 mg/kgdose was essentially without effect. The single-cleaved c7E3 and salinecontrol groups showed similar profiles throughout the 96-hour monitoringperiod. The platelet count declines at the final 96-hour determinationin both the saline control group and single-cleaved c7E3 group suggesteda non-immune-mediated cause (e.g. blood volume losses from the repeatedsampling).

Platelet counts in the intact c7E3 IgG group showed a gradual recoveryreaching approximately 50% of the pre-dose level by 96 hours. No adverseclinical findings (e.g. bleeding) were noted in any group and this isconsistent with the known human tolerance for limited periods of lowcirculating platelet counts and/or profound inhibition of platelets.

The finding in this study was that single proteolytic cleavage of IgG inthe lower hinge results in profound loss of effector function. Despiteits equivalent binding to platelets, the single cleaved derivative ofc7E3 was unable to engage the components of the immune system thatnormally remove opsonized cells (as seen with intact c7E3 in thisstudy). These in vivo results confirmed similar in vitro findings withseveral cell-targeting mAbs whose single-cleaved derivatives essentiallylose all effector functions in ADCC and complement assays.

To be consistent with the prior experiments, the variants of c7E3 wereall administered at the 0.05 mg/kg dose. The study protocol included 7different groups of 3 animals as listed in Table 6. The unique aspect ofthe experiment (groups 6 and 7) involves the infusion of the firsttargeting mAb followed by the cleavage site specific mAb after a 10minute delay. The cleavage site specific IdeS cleavage site mAb, 2095-2,was administered at 0.5 mg/kg; 10-fold higher than the dose used for allof the c7E3 variants. The higher dose was chosen in order to maximizethe complexation of cleavage site specific mAb with platelet-bound c7E3variants. All mAbs were delivered by slow infusion over a 20 minuteperiod. Platelet counts were monitored over a 96-hour period. Theplatelet counts were normalized to the pre-dose count within each animalfor clarity of presentation and to minimize the normal variability innumerical platelet counts in these small 3-animal groups.

TABLE 6 Study protocol for restoration of function study in dogs.Duration Duration Blood collection of 1^(st) of 2nd times (H after GroupTest article(s) infusion Delay infusion start) 1 Normal saline for 20min NA NA Predose, 2, 24, injection 48, 72, 96 2 c7E3 IgG @ 0.05 20 minNA NA Predose, 2, 24, mg/kg 48, 72, 96 3 c7E3 F(ab′)₂ @ 0.05 20 min NANA Predose, 2, 24, mg/kg 48, 72, 96 4 c7E3 sc IgG @ 0.05 20 min NA NAPredose, 2, 24, mg/kg 48, 72, 96 5 mAb 2095-2 @ 0.5 20 min NA NAPredose, 2, 24, mg/mg 48, 72, 96 6 c7E3 F(ab′)₂ @ 0.05 20 min 10 min 20min Predose, 2, 24, mg/kg + mAb 2095-2 @ 0.5 48, 72, 96 mg/mg 7 c7E3 scIgG @ 0.05 20 min 10 min 20 min Predose, 2, 24, mg/kg + mAb 2095-2 @ 0.548, 72, 96 mg/mg

The results are presented in FIG. 16. A number of findings emerged fromthis study. As the dose finding studies show, intact c7E3 IgGadministered at 0.05 mg/kg, induced substantial platelet clearance witha nadir apparent at 24-48 hours. Recovery of platelet numbers began atapproximately 72 hours and slowly increased through the 96-hourdetermination. An additional blood sample was incorporated into thestudy at 7 days (168 hours) to allow an assessment if full recoverywould occur. Full recovery did occur in all applicable treatment groupsby 7 days.

In contrast to intact c7E3 IgG, single-cleaved IgG and F(ab′)₂ werewithout effect on platelet numbers and the platelet number changes inthese groups was not different from the saline control group. Likewisethe cleavage site specific mAb, 2095-2, when infused alone (group 5) hadno measurable impact on circulating platelets. However, in the c7E3F(ab′)₂ plus mAb 2095-2 group, there occurred a rapid decrease of theplatelet count such that at 2 hours the effect was nearly maximal. Inaddition, the extent of the platelet decline appeared to be greater inthe groups where the cleavage site specific antibody was administeredafter the cleaved antibody fractions than in the group receiving intactc7E3 IgG (alone; group 2) at the 2 and 24 hour determinations.Thereafter, platelet counts gradually recovered and by 48 hours the rateof recovery paralleled that in the intact c7E3 IgG group.

In the F(ab′)₂ combination group, when mAb 2095-2 was coupled withsingle-cleaved c7E3 IgG the extent of platelet clearance was not asmarked as seen in the F(ab′)₂ group and may be attributable to onepoorly responsive animal in the scIgG group (also reflected in the wideerror bars for this group). Nevertheless, platelet clearance occurredmore quickly than had been evident in the intact c7E3 IgG group. ThescIgG result is important since the targeting of this derivative withthe mAb in vivo appears to have been as effective as the targeting ofF(ab′)₂—an outcome that was not predictable based on in vitro findings.

Discussion/Conclusions

The series of animal studies described here confirmed earlier in vitrofindings that single-cleaved proteolytic derivatives of IgGs lose theability to remove cells to which they are bound—in this case in vivo.The intact c7E3 IgG was shown to induce platelet clearance within 24hours in the dog at doses ≧0.05 mg/kg. The 0.05 mg/kg dose wascalculated to be sufficient to provide several thousand copies of IgGper platelet or about 5% α_(IIb)β₃ receptor blockade. A substantiallyhigher level of receptor blockade is known to be required for inhibitionof platelet function (about 80,000 copies per platelet). Thus, thecanine immune system has the capacity to clear cells that are opsonizedwith IgG at this fractional level.

The results showed that a single proteolytic cleavage of the human IgG1lower hinge abrogated the platelet clearance properties of the c7E3 IgG.Here, the functionally-inactive, single-cleaved IgG was prepared ex vivoby partial digestion with IdeS protease, however, and as demonstratedherein, other proteases yield IgGs with similar loss of function. Thesingle IdeS cleavage did not impact the antigen binding characteristicsof c7E3 as shown in an in vitro platelet inhibition assay. The findingssuggested a mechanism to explain certain shortcomings of host immunesystems in pathologies associated with hostile proteolytic environments(e.g. certain tumors, bacterial infections, inflammatory settings).

The study findings pointed to a means to correct the proteolytic defectin IgGs. Namely, a specific mAb vs. the site of proteolytic cleavageshould deposit a functional Fc domain on the inactive cell-boundantibody and thereby restore Fc-mediated effector functions.

A monoclonal antibody to the IdeS cleavage site in the IgG hinge wasgenerated by immunization of rabbits. This mAb, 2095-2, aftermodification to incorporate human constant regions, readily restored invitro cell killing to inactive F(ab′)₂ or single-cleaved IgGs in ADCCand complement assays.

The key test was to employ 2095-2 in combination with IdeS-generatedproteolytic derivatives of c7E3 IgG in vivo. The 2-stage protocol wasdesigned to allow c7E3 to first bind to platelets and to then followwith an excess of the cleavage site specific mAb to complex with theplatelet bound c7E3s. In the presence of coupled anti-cleaved hinge Maband a cleaved Mab, platelet clearance was more rapid and the degree ofacute platelet clearance more profound (with c7E3 F(ab′)₂) than wasinduced with intact c7E3 IgG alone. The rapidity of platelet clearancewith the combined therapies is suggestive of an enhanced mode of immunecell killing/removal.

Example 15 Cleavage Site Specific Vaccination to Treat Cancer

The use of a hinge analogue peptide vaccination has potential to treatchronic human diseases such as invasive and metastatic cancer. Severalinvasive cancer animal models currently exist which are suitable fortesting the efficacy of cleavage site specific directed vaccination as ameans to treat invasive cancer.

The vaccination approach would confer a markedly differentpharmacodynamic profile compared to anti-tumor mAb therapy alone. In thelatter, an established tumor is subjected to an abrupt dosage of amonoclonal antibody to a specific target on its surface. The tumor may,or may not, already be targeted by host antibodies to the same antigen,or to additional antigens, on those cells. The vaccination strategy, ifinitiated early, would provide a continuous and comparatively invariantlevel of cleavage site specific host antibodies to engage anytumor-surface cleaved antibodies present at the sites of tumor growth orinvasion as generated.

As demonstrated by using the innate humoral response of the rabbit inthe previously described infection model, the cellular target of theprimary response is almost immaterial; the secondary antibody waverestores effector function to any damaged primary antibody that ispresent. The inactivated and cell-bound-bound host antibodies wouldprovide a variety of antigenic targets (and surface locations) forcleavage site specific Abs.

As demonstrated herein, a single- or double-cleaved antibody directed toand engaged with a cell surface antigen can be targeted by a cleavagesite-specific antibody, thereby restoring the host ability to eliminatethe target cell using effector functions provided by the intact cleavagesite specific antibody. Another and markedly different approach would beto immunize the host against the sites of cleavage damage induced byproteases associated with specific diseases such as metastatic cancer.For example, tumor cells elaborate matrix metalloproteases that cleaveIgG in the hinge. Vaccination against the sites of cleavage couldprovide host antibodies that would combat the molecular defects andaugment immune function in that local environment.

The target of the damaged mAb(s) could be specific or could bemultiply-targeted using a mixture of cleavage site specific peptides inorder to protect against the action of multiple proteolytic enzymeswithout the need for detailed identification.

Thus, in accordance with the invention, a subject cancer patient in needof treatment, is vaccinated with a cleavage site peptide immunogen togenerate a cleavage site specific antibody response either before, afteror concurrent with treatment within a cancer treating antibodycomposition. In one instance, the immunogen is a MMP-3 or MMP-12cleavage site peptide having the sequence terminating in the amino acidsequence P-C-P-A-P which is residues 10 to 14 of SEQ ID NO: 1.

1. An isolated antibody composition that comprises at least one antibodythat specifically binds to a single cleaved_IgG protease cleavageproduct characterized by, a) having a molecular weight of 135 kDa and b)is formed by a single proteolytic cleavage on one of the heavy chains inthe lower hinge domain of an IgG molecule c) wherein the antibody doesnot react with intact IgG.
 2. The antibody composition of claim 1 whichcomprises a polyclonal antiserum.
 3. The antibody composition of claim 1which comprises at least one monoclonal antibody.
 4. The antibodycomposition of claim 1 which specifically binds to a protease specificcleavage site in human IgG1 produced by a protease selected from thegroup consisting of a MMP-3, MMP-7, MMP-12, HNE, plasmin, cathepsin G,pepsin, IdeS, or glutamyl endopeptidase I from Staph. aureus.
 5. Theantibody composition of claim 1, comprising an antibody generated byimmunization of an animal, or screening of an antibody library, with acleavage product analogue peptide prepared by: a) identifying theresidue of a pair of residues of a heavy chain of an antibody cleaved bya protease most proximal to the N-terminus of the heavy chain; b)identifying a peptide sequence comprising at least 5 contiguous aminoacid residues which are upstream from the protease cleavage site wherethe residue of the protease cleavage site that is most proximal to theN-terminus of the polypeptide will become the C-terminus of the definedsequence; c) creating a solution of the peptide, peptide homolog orchemical homolog in sufficient amounts for the immunization orscreening; d) administering the peptide or peptide homolog or chemicalhomolog to the animal; and e) isolating the antibody capable of specificbinding to the peptide, peptide homolog or chemical homolog.
 6. Anisolated antibody composition of claim 1 that contains at least oneantibody that specifically binds to a polypeptide comprising at least 5contiguous amino acids selected from the human IgG hinge regionsequences of SEQ ID NO: 1, 2, 3, or 4 that are upstream from the aminoterminal side of a protease cleavage site wherein the antibodycomposition does not bind to intact IgG.
 7. The antibody composition ofclaim 6 wherein the antibody is capable of specifically binding apeptide epitope which is downstream from the hinge core of IgG1, definedas the residues T-C-P-P-C- (residues 7-11 of SEQ ID NO: 1).
 8. Theantibody composition of claim 6 wherein the polypeptide is a 12-merpeptide analogue of the human IgG1 lower hinge and adjoining CH2 domainhaving the sequence TCPPCPAPELLG (residues 7-18 of SEQ ID NO: 1).
 9. Theantibody composition of claim 1 which specifically binds to a cleavageproduct peptide analogue comprising a peptide having an amino acidsequence selected from SEQ ID NO: 5-16 and N-terminal truncationsthereof, comprising at least 5 amino acids and containing amino acidsequences upstream of the N-terminal side of an IgG protease cleavagesite.
 10. The antibody composition of claim 1 which specifically bindsto a polypeptide having an amino acid sequence selected from SEQ ID NO:5-16.
 11. The antibody composition of claim 1 that specifically binds toa polypeptide having an amino acid sequence selected from (a) a peptidecomprising the sequence of amino acids on the amino terminal side of anIgG1 MMP-3 cleavage site (TCPPCPAP, residues 7-14 of SEQ ID NO: 1), (b)or a peptide comprising the glutamyl endopeptidase I IgG1 cleavage site(TCPPCPAPE, residues 7-15 of SEQ ID NO: 1); or (c) a peptide comprisingthe IdeS IgG1 cleavage site (TCPPCPAPELLG, residues 7-18 of SEQ ID NO:1).
 12. An isolated human IgG protease cleavage site peptide consistingof an amino acid sequence selected from the group consisting of SEQ IDNO: 5-16 or an analogue thereof having one or more conservative aminoacid substitutions.
 13. The human IgG protease cleavage site peptideanalogue of claim 12, wherein the cysteine residues are replaced withserine residues.
 14. The peptide of claim 12 conjugated to a carrierprotein in a manner such that the C-terminus of the peptide ischemically bound to a carrier protein.
 15. The peptide conjugate ofclaim 14, wherein the carrier protein is selected from the groupconsisting of keyhole limpet hemocyanin (KLH) or serum albumin.
 16. Ananimal immunized with the peptide analogue according to any of claim12-16.
 17. The animal of claim 16 wherein the animal is a rabbit.
 18. Amethod of preparing the antibody composition of claim 1 using theimmunized animal of claim 16, wherein the reagent is purified from theserum of said animal by pre-absorption on a human IgG affinity matrix.19. The method of preparing an antibody of claim 18, wherein theantibody is humanized.
 20. A method of protecting a human subject from apathological condition characterized by the release of a protease,wherein the method comprises administering an antibody of claim
 1. 21.The method of claim 20, wherein the disease is selected from anarthritic disease, a malignant disease, the presence of an infectiousagent or a parasite, and a vascular disease.
 22. The method of claim 21,wherein the disease is rheumatoid arthritis.
 23. The method of claim 21,wherein the disease is a Stapholycoccus spp. Infection.
 24. The methodof claim 21, wherein the disease is breast cancer.
 25. The method ofclaim 21, wherein the subject has been diagnosed or suspected of havinghad a myocardial infarction or is suffering from congestive heartfailure.
 26. The method of claim 20, wherein the antibody recognizes aprotease specific cleavage site in human IgG1 produced by a proteaseselected from the group consisting of a MMP-3, MMP-7, MMP-12, HNE,plasmin, cathepsin G, pepsin, IdeS, or glutamyl endopeptidase I fromStaph. aureus.
 27. The use of an antibody composition of claim 1 torestore effector function of an antibody used to treat a pathologicalcondition, wherein the antibody used to treat the pathological conditionis subject to cleavage by one or more proteases.
 28. A method ofprotecting a human subject from a pathological condition characterizedby the release of a protease, wherein the method comprises administeringa peptide of claim 12 to the subject in order to elicit an antibodyhaving the immunospecificity of the antibody of claim
 1. 29. A method ofrestoring effector function to an antibody used to treat a pathologicalcondition, where the antibody used to treat the pathological conditionis subject to cleavage by one or more proteases, which method comprisesadministering an antibody of claim 1 before, after or concurrent withthe administration of the antibody used to treat the pathologicalcondition.
 30. The method of claim 29 wherein the pathological conditionis cancer and wherein the antibody used to treat the pathologicalcondition depends, at least in part, on its effector function.
 31. Amethod for enhancing or maintaining effector function of an antibodyadministered to a patient for the treatment of a pathological condition,wherein the antibody is subject to cleavage by one or more proteases inthe patient, which method comprises vaccinating the patient before,after or concurrently with the antibody treatment, with a human IgGprotease cleavage site peptide capable of generating antibodies thatbind to the treatment antibody and can restore effector functionthereto.
 32. The method of claim 31 wherein the human IgG proteasecleavage site peptide used for vaccinating the patient is a peptideselected from those of SEQ ID. NO: 5-16.
 33. A vaccine compositioncomprising the human IgG cleavage site peptide of claim 12 inassociation with one or more pharmaceutically acceptable carriers oradjuvants.
 34. The vaccine composition of claim 33 where the adjuvant isselected from the group consisting of alum, incomplete Freund'sadjuvant, complete Freund's adjuvant or MF59.
 35. A kit including areagent for detection of a disease marker in tissue of a subject, whichreagent comprises at least one antibody that specifically binds to asingle cleaved_IgG protease cleavage product characterized by, a) havinga molecular weight of 135 kDa and b) is formed by a single proteolyticcleavage on one of the heavy chains in the lower hinge domain of an IgGmolecule c) wherein the antibody does not react with intact IgG.